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• There are 379 unique proteins containing the PTMs that associate with disease.
Alternating hemiplegia of childhood (AHC) is an ultra-rare neurological disorder named for the transient episodes, often referred to as "attacks", of hemiplegia (weakness or paralysis) that those with the condition experience. It typically presents before the age of 18 months. These hemiplegic attacks can cause anything from mild weakness to complete paralysis on one or both sides of the body, and they can vary greatly in duration. Attacks may also alternate from one side of the body to the other, or alternate between affecting one or both sides during a single attack. Besides hemiplegia, symptoms of the disorder include an extremely broad range of neurological and developmental impairments which are not well understood. Normally, hemiplegia and other associated symptoms cease completely with sleep, but they may recur upon waking.
Most frequently AHC is caused by a spontaneous mutation in the ATP1A3 gene. It is an extremely rare disorder ¨C approximately one in one million people have AHC. It was only recently discovered, having first been characterized in 1971. Reference Wiki: Alternating hemiplegia of childhood | Amyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND) or Lou Gehrig's disease in the United States, is a rare but terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and, lastly, breathe are all lost. While only 15% of people with ALS also fully develop frontotemporal dementia, an estimated 50% face at least some minor difficulties with thinking and behavior. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset (begins with weakness in the arms or legs) or bulbar-onset (begins with difficulty in speaking or swallowing).
Most cases of ALS (about 90% to 95%) have no known cause, and are known as sporadic ALS. However, both genetic and environmental factors are believed to be involved. The remaining 5% to 10% of cases have a genetic cause, often linked to a history of the disease in the family, and these are known as familial ALS (hereditary). About half of these genetic cases are due to disease-causing variants in one of four specific genes. The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.
There is no known cure for ALS. The goal of treatment is to slow the disease progression, and improve symptoms. Treatments that slow ALS include riluzole (extends life by two to three months) and sodium phenylbutyrate/ursodoxicoltaurine (extends life by around seven months). Non-invasive ventilation may result in both improved quality, and length of life. Mechanical ventilation can prolong survival but does not stop disease progression. A feeding tube may help maintain weight and nutrition. Death is usually caused by respiratory failure. The disease can affect people of any age, but usually starts around the age of 60. The average survival from onset to death is two to four years, though this can vary, and about 10% of those affected survive longer than ten years.
Descriptions of the disease date back to at least 1824 by Charles Bell. In 1869, the connection between the symptoms and the underlying neurological problems was first described by French neurologist Jean-Martin Charcot, who in 1874 began using the term amyotrophic lateral sclerosis. Reference Wiki: Amyotrophic lateral sclerosis | Amyotrophy (1) Amyotrophy is progressive wasting of muscle tissues. Muscle pain is also a symptom. It can occur in middle-aged males with type 2 diabetes. It also occurs with motor neuron disease. Reference Wiki: Amyotrophy |
Arthrogryposis (9) Arthrogryposis (AMC) describes congenital joint contracture in two or more areas of the body. It derives its name from Greek, literally meaning 'curving of joints' (arthron, 'joint'; gr?p¨sis, late Latin form of late Greek gr¨±p¨sis, 'hooking').
Children born with one or more joint contractures have abnormal fibrosis of the muscle tissue causing muscle shortening, and therefore are unable to perform active extension and flexion in the affected joint or joints.
AMC has been divided into three groups: amyoplasia, distal arthrogryposis, and syndromic (is a syndrome or part of a syndrome]]. Amyoplasia is characterized by severe joint contractures and muscle weakness. Distal arthrogryposis mainly involves the hands and feet. Types of arthrogryposis with a primary neurological or muscle disease belong to the syndromic group.
Reference Wiki: Arthrogryposis | Limb¨Cgirdle muscular dystrophy (LGMD) is a genetically heterogeneous group of rare muscular dystrophies that share a set of clinical characteristics. It is characterised by progressive muscle wasting which affects predominantly hip and shoulder muscles. LGMD usually has an autosomal pattern of inheritance. It currently has no known cure or treatment.
LGMD may be triggered or worsened in genetically susceptible individuals by statins, because of their effects on HMG-CoA reductase Reference Wiki: Autosomal recessive limb-girdle muscular dystrophy type | Becker muscular dystrophy (BMD) is an X-linked recessive inherited disorder characterized by slowly progressing muscle weakness of the legs and pelvis. It is a type of dystrophinopathy. The cause is mutations and deletions in any of the 79 exons encoding the large dystrophin protein, essential for maintaining the muscle fiber's cell membrane integrity. Becker muscular dystrophy is related to Duchenne muscular dystrophy in that both result from a mutation in the dystrophin gene, however the hallmark of Becker is milder in-frame deletions. and hence has a milder course, with patients maintaining ambulation till 50¨C60 years if detected early.
While there is no known cure, management strategies such as physical therapy, braces, and corrective surgery may alleviate symptoms. Assisted ventilation may be required in those with weakness of breathing muscles. Several drugs designed to address the root cause are currently available including gene therapy (Elevidys).
Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells. These patients do not require antisense drugs (Ataluren, Eteplirsen etc.) as certain percentage of dystrophin is already expressed.
Reference Wiki: Becker muscular dystrophy |
Bethlem myopathy (3) Bethlem myopathy is predominantly an autosomal dominant myopathy, classified as a congenital form of limb-girdle muscular dystrophy. There are two types of Bethlem myopathy, based on which type of collagen is affected.
Bethlem myopathy 1 (BTHLM1) is caused by a mutation in one of the three genes coding for type VI collagen. These include COL6A1, COL6A2, and COL6A3. It is typically autosomal dominant, though uncommonly can be autosomal recessive.
Bethlem myopathy 2 (BTHLM2), formerly known as myopathic-type Ehlers¨CDanlos syndrome, is caused by a mutation on the COL12A1 gene coding for type XII collagen. It is autosomal dominant.
In 2017, an international workshop proposed a redefined criteria and naming system for limb-girdle muscular dystrophies. Bethlem myopathy 1 (collagen VI) was included into the proposed list and renamed LGMDD5 for autosomal dominant mutations and LGMDR22 for recessive mutations. Bethlem myopathy 2 (collagen XII) was not addressed.
Gowers's sign, toe walking, multiple contractures of the joints (especially the fingers: 'Bethlem sign'), skin abnormalities, and muscle weakness (proximal more than distal) are typical signs and symptoms of the disease. Initially, in early childhood, there may also be joint laxity. There is no cardiac involvement in either Bethlem myopathy 1 or 2, which helps to differentiate it from Emery¨CDreifuss muscular dystrophy. Currently there is no cure for the disease and symptomatic treatment is used to relieve symptoms and improve quality of life.
Bethlem myopathy may be diagnosed based on clinical examinations and laboratory tests may be recommended. Genetic testing for known pathological variants is preferred. In the case of a VUS, testing of dermal fibroblast culture is used for an accurate diagnosis.
Bethlem myopathy 1 is a rare disease, affecting about 1 in 200,000 people. Bethlem myopathy 2 is an ultra-rare disease, affecting less than 1 in 1,000,000 people.
The condition was described by J. Bethlem and G. K. van Wijngaarden in 1976. Reference Wiki: Bethlem myopathy | Brody myopathy (1) Brody myopathy, also called Brody disease, is a rare disorder that affects skeletal muscle function. BD was first characterized in 1969 by Dr. Irwin A. Brody at Duke University Medical Center. Individuals with BD have difficulty relaxing their muscles after exercise. This difficulty in relaxation leads to symptoms including cramps, stiffness, and discomfort in the muscles of the limbs and face. Symptoms are heightened by exercise and commonly progress in severity throughout adulthood. Reference Wiki: Brody myopathy | Collagen VI (ColVI) is a type of collagen primarily associated with the extracellular matrix of skeletal muscle. ColVI maintains regularity in muscle function and stabilizes the cell membrane. It is synthesized by a complex, multistep pathway that leads to the formation of a unique network of linked microfilaments located in the extracellular matrix (ECM). ColVI plays a vital role in numerous cell types, including chondrocytes, neurons, myocytes, fibroblasts, and cardiomyocytes. ColVI molecules are made up of three alpha chains: ¦Á1(VI), ¦Á2(VI), and ¦Á3(VI). It is encoded by 6 genes: COL6A1, COL6A2, COL6A3, COL6A4, COL6A5, and COL6A6. The chain lengths of ¦Á1(VI) and ¦Á2(VI) are about 1,000 amino acids. The chain length of ¦Á3(VI) is roughly a third larger than those of ¦Á1(VI) and ¦Á2(VI), and it consists of several spliced variants within the range of 2,500 to 3,100 amino acids.
The first two alpha chains subunits of ColVI have a molecular weight of 140-150 KDa and the third polypeptide chain is larger with a molecular weight of 250-300kDa. ColVI is also found in the skin, lungs, blood vessels, cornea and intervertebral disc. It also forms part of the peripheral nerves, brain, myocardium and adipose tissue. Reference Wiki: Collagen VI-related myopathy |
Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time. The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin. Some types are also associated with problems in other organs.
Over 30 different disorders are classified as muscular dystrophies. Of those, Duchenne muscular dystrophy (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four. Other relatively common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy, whereas limb¨Cgirdle muscular dystrophy and congenital muscular dystrophy are themselves groups of several ¨C usually extremely rare ¨C genetic disorders.
Muscular dystrophies are caused by mutations in genes, usually those involved in making muscle proteins. The muscle protein, dystrophin, is in most muscle cells and works to strengthen the muscle fibers and protect them from injury as muscles contract and relax. It links the muscle membrane to the thin muscular filaments within the cell. Dystrophin is an integral part of the muscular structure. An absence of dystrophin can cause impairments: healthy muscle tissue can be replaced by fibrous tissue and fat, causing an inability to generate force. Respiratory and cardiac complications can occur as well. These mutations are either inherited from parents or may occur spontaneously during early development. Muscular dystrophies may be X-linked recessive, autosomal recessive, or autosomal dominant. Diagnosis often involves blood tests and genetic testing.
There is no cure for any disorder from the muscular dystrophy group. Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.). Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells. Physical therapy, braces, and corrective surgery may help with some symptoms while assisted ventilation may be required in those with weakness of breathing muscles.
Outcomes depend on the specific type of disorder. Many affected people will eventually become unable to walk and Duchenne muscular dystrophy in particular is associated with shortened life expectancy.
Muscular dystrophy was first described in the 1830s by Charles Bell. The word "dystrophy" comes from the Greek dys, meaning "no, un-" and troph- meaning "nourish".
Reference Wiki: Congenital muscular dystrophy | Congenital myopathy (13) Congenital myopathy is a very broad term for any muscle disorder present at birth. This defect primarily affects skeletal muscle fibres and causes muscular weakness and/or hypotonia. Congenital myopathies account for one of the top neuromuscular disorders in the world today, comprising approximately 6 in 100,000 live births every year. As a whole, congenital myopathies can be broadly classified as follows:
A distinctive abnormality in skeletal muscle fibres on the cellular level; observable via light microscope
Symptoms of muscle weakness and hypotonia
Is a congenital disorder, meaning it occurs during development and symptoms present themselves at birth or in early life.
Is a genetic disorder. Reference Wiki: Congenital myopathy | Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy predominantly affecting boys. The onset of muscle weakness typically begins around age four, with rapid progression. Initially, muscle loss occurs in the thighs and pelvis, extending to the arms, which can lead to difficulties in standing up. By the age of 12, most individuals with Duchenne muscular dystrophy are unable to walk. Affected muscles may appear larger due to an increase in fat content, and scoliosis is common. Some individuals may experience intellectual disability, and females carrying a single copy of the mutated gene may show mild symptoms.
Duchenne muscular dystrophy is caused by mutations and/or deletions in any of the 79 exons encoding the large dystrophin protein, which is essential for maintaining the muscle fiber's cell membrane integrity. The disorder follows an X-linked recessive inheritance pattern, with approximately two-thirds of cases inherited from the mother and one-third resulting from a new mutation. Diagnosis can frequently be made at birth through genetic testing, and elevated creatine kinase levels in the blood are indicative of the condition.
While there is no known cure, management strategies such as physical therapy, braces, and corrective surgery may alleviate symptoms. Assisted ventilation may be required in those with weakness of breathing muscles. Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.). Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells.
Various figures of the occurrence of Duchenne muscular dystrophy are reported. One source reports that it affects about one in 3,500 to 6,000 males at birth. Another source reports Duchenne muscular dystrophy being a rare disease and having an occurrence of 7.1 per 100,000 male births. A number of sources referenced in this article indicate an occurrence of 6 per 100,000.
Duchenne muscular dystrophy is the most common type of muscular dystrophy, with a median life expectancy of 28¨C30 years. However, with comprehensive care, some individuals may live into their 30s or 40s. Duchenne muscular dystrophy is considerably rarer in females, occurring in approximately one in 50,000,000 live female births. Reference Wiki: Duchenne muscular dystrophy |
Dystonia (25) A dystopia (from Ancient Greek ¦Ä¦Ô¦Ò (dus) 'bad', and ¦Ó?¦Ð¦Ï? (t¨®pos) 'place'), also called a cacotopia or anti-utopia, is a community or society that is extremely bad or frightening. It is often treated as an antonym of utopia, a term that was coined by Sir Thomas More and figures as the title of his best known work, published in 1516, which created a blueprint for an ideal society with minimal crime, violence, and poverty. The relationship between utopia and dystopia is in actuality, not one simple opposition, as many utopian elements and components are found in dystopias as well, and vice versa.
Dystopias are often characterized by fear or distress, tyrannical governments, environmental disaster, or other characteristics associated with a cataclysmic decline in society. Themes typical of a dystopian society include: complete control over the people in a society through the usage of propaganda, heavy censoring of information or denial of free thought, worshiping an unattainable goal, the complete loss of individuality, and heavy enforcement of conformity. Despite certain overlaps, dystopian fiction is distinct from post-apocalyptic fiction, and an undesirable society is not necessarily dystopian. Dystopian societies appear in many fictional works and artistic representations, particularly in stories set in the future. Famous examples include Yevgeny Zamyatin's We (1920), Aldous Huxley's Brave New World (1932), George Orwell's Nineteen Eighty-Four (1949), and Ray Bradbury's Fahrenheit 451 (1953). Dystopian societies appear in many sub-genres of fiction and are often used to draw attention to society, environment, politics, economics, religion, psychology, ethics, science, or technology. Some authors use the term to refer to existing societies, many of which are, or have been, totalitarian states or societies in an advanced state of collapse. Dystopias, through an exaggerated worst-case scenario, often make a criticism about a current trend, societal norm, or political system.
Reference Wiki: Dystonia | A dystonia characterized by recurrent brief involuntary hyperkinesias triggered by sudden movements that has_material_basis_in autosomal dominant inheritance of heterozygous mutation in the proline-rich transmembrane protein 2 gene (PRRT2) on chromosome 16p11. Reference DiseaseOntology: Episodic kinesigenic dyskinesia | Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time. The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin. Some types are also associated with problems in other organs.
Over 30 different disorders are classified as muscular dystrophies. Of those, Duchenne muscular dystrophy (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four. Other relatively common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy, whereas limb¨Cgirdle muscular dystrophy and congenital muscular dystrophy are themselves groups of several ¨C usually extremely rare ¨C genetic disorders.
Muscular dystrophies are caused by mutations in genes, usually those involved in making muscle proteins. The muscle protein, dystrophin, is in most muscle cells and works to strengthen the muscle fibers and protect them from injury as muscles contract and relax. It links the muscle membrane to the thin muscular filaments within the cell. Dystrophin is an integral part of the muscular structure. An absence of dystrophin can cause impairments: healthy muscle tissue can be replaced by fibrous tissue and fat, causing an inability to generate force. Respiratory and cardiac complications can occur as well. These mutations are either inherited from parents or may occur spontaneously during early development. Muscular dystrophies may be X-linked recessive, autosomal recessive, or autosomal dominant. Diagnosis often involves blood tests and genetic testing.
There is no cure for any disorder from the muscular dystrophy group. Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.). Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells. Physical therapy, braces, and corrective surgery may help with some symptoms while assisted ventilation may be required in those with weakness of breathing muscles.
Outcomes depend on the specific type of disorder. Many affected people will eventually become unable to walk and Duchenne muscular dystrophy in particular is associated with shortened life expectancy.
Muscular dystrophy was first described in the 1830s by Charles Bell. The word "dystrophy" comes from the Greek dys, meaning "no, un-" and troph- meaning "nourish".
Reference Wiki: Facioscapulohumeral muscular dystrophy |
Congenital fibrosis of the extraocular muscles is a class of rare genetic disorders affecting one or more of the muscles that move the eyeballs. Individuals with congenital fibrosis of the extraocular muscles (CFEOM) have varying degrees of ophthalmoplegia (an inability to move the eyes in one or more directions) and ptosis. The condition is present from birth, non-progressive, runs in families, and usually affects both eyes similarly. In the most common form, the superior recti are dysfunctional and the inferior recti, lacking proper opposition, pull the eyes down, forcing the head to be tilted upward in order to see straight ahead.
There are three types of CFEOM, numbered 1-3. CFEOM1, the most common type, is now known to be caused by one of several mutations in the KIF21A gene, while CFEOM2 is caused by mutations in the PHOX2A gene. CFEOM3 is caused by mutations in the TUBB3 gene.
CFEOM was first named in 1956, although papers describing conditions now known or assumed to be CFEOM appear in the medical literature as early as 1840. Due to its rarity, it has been independently cited numerous times under many different names. Reference Wiki: Fibrosis of extraocular muscles | Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles.
HIBMs are a group of muscle wasting disorders that are uncommon in the general world population. One autosomal recessive form of HIBM is known as IBM2 or GNE myopathy, which is a common genetic disorder amongst people of Iranian Jewish descent. IBM2 has also been identified in other minorities throughout the world, including those of Asian, European, and South American, and Middle Eastern descent. In Japan and other East Asian countries, this disorder is known as distal myopathy with rimmed vacuoles (DMRV).
IBM2 causes progressive muscle weakness and wasting. Muscle wasting usually starts around the age of 20 ¨C 30 years, although young onset at 17 and old onset at 52 has been recorded. It can progress to marked disability within 10 to 15 years, causing many people with IBM2 to become full-time wheelchair users. The weakness and severity can vary from person to person. In some, weakness in the legs is noticed first. In some others, the hands are weakened more rapidly than the legs. IBM2 does not seem to affect the brain, internal organs or sensation. The quadriceps are relatively spared, and remain strong until the late stages of disease, which is the reason IBM2 is often referred to as quadriceps sparing myopathy (QSM). Reference Wiki: Hereditary inclusion body myopathy | Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body myopathies comprise both autosomal recessive and autosomal dominant muscle disorders that have a variable expression (phenotype) in individuals, but all share similar structural features in the muscles. Reference Wiki: Inclusion body myopathy |
Spinal muscular atrophy (SMA) is a rare neuromuscular disorder that results in the loss of motor neurons and progressive muscle wasting. It is usually diagnosed in infancy or early childhood and if left untreated it is the most common genetic cause of infant death. It may also appear later in life and then have a milder course of the disease. The common feature is progressive weakness of voluntary muscles, with arm, leg and respiratory muscles being affected first. Associated problems may include poor head control, difficulties swallowing, scoliosis, and joint contractures.
The age of onset and the severity of symptoms form the basis of the traditional classification of spinal muscular atrophy into a number of types.
Spinal muscular atrophy is due to an abnormality (mutation) in the SMN1 gene which encodes SMN, a protein necessary for survival of motor neurons. Loss of these neurons in the spinal cord prevents signalling between the brain and skeletal muscles. Another gene, SMN2, is considered a disease modifying gene, since usually the more the SMN2 copies, the milder is the disease course. The diagnosis of SMA is based on symptoms and confirmed by genetic testing.
Usually, the mutation in the SMN1 gene is inherited from both parents in an autosomal recessive manner, although in around 2% of cases it occurs during early development (de novo). The incidence of spinal muscular atrophy worldwide varies from about 1 in 4,000 births to around 1 in 16,000 births, with 1 in 7,000 and 1 in 10,000 commonly quoted for Europe and the US respectively.
Outcomes in the natural course of the disease vary from death within a few weeks after birth in the most acute cases to normal life expectancy in the protracted SMA forms. The introduction of causative treatments in 2016 has significantly improved the outcomes. Medications that target the genetic cause of the disease include nusinersen, risdiplam, and the gene therapy medication onasemnogene abeparvovec. Supportive care includes physical therapy, occupational therapy, respiratory support, nutritional support, orthopaedic interventions, and mobility support. Reference Wiki: Kugelberg-Welander disease | An alpha thalassemia that has_material_basis_in a deletion in chromosome 16p that involves the alpha-1 (HBA1) and alpha-2 (HBA2) genes, among others. Reference DiseaseOntology: Laminin alpha 2-related dystrophy | |
leiomyomatosis (1) | Leiomyosarcoma (215) A smooth muscle cancer that can arise almost anywhere in the body, but is most common in the uterus, abdomen, or pelvis. Reference DiseaseOntology: Leiomyosarcoma | Limb¨Cgirdle muscular dystrophy (LGMD) is a genetically heterogeneous group of rare muscular dystrophies that share a set of clinical characteristics. It is characterised by progressive muscle wasting which affects predominantly hip and shoulder muscles. LGMD usually has an autosomal pattern of inheritance. It currently has no known cure or treatment.
LGMD may be triggered or worsened in genetically susceptible individuals by statins, because of their effects on HMG-CoA reductase Reference Wiki: Limb-girdle muscular dystrophy |
In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease (Greek : myo- muscle + patheia -pathy : suffering). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("neuropathies" or "neurogenic" disorders) or elsewhere (e.g., the brain).
This muscular defect typically results in myalgia (muscle pain), muscle weakness (reduced muscle force), or premature muscle fatigue (initially normal, but declining muscle force). Muscle cramps, stiffness, spasm, and contracture can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as muscle atrophy (abnormally small) or a pseudoathletic appearance (abnormally large).
Capture myopathy can occur in wild or captive animals, such as deer and kangaroos, and leads to morbidity and mortality. It usually occurs as a result of stress and physical exertion during capture and restraint.
Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Some conditions, such as myositis, can be considered both neuromuscular and musculoskeletal. Different myopathies may be inherited, infectious, non-communicable, or idiopathic (cause unknown). The disease may be isolated to affecting only muscle (pure myopathy), or may be part of a systemic disease as is typical in mitochondrial myopathies. Reference Wiki: Megaconial type congenital muscular dystrophy | Multiple sclerosis (MS) is an autoimmune disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This damage disrupts the ability of parts of the nervous system to transmit signals, resulting in a range of signs and symptoms, including physical, mental, and sometimes psychiatric problems. Specific symptoms can include double vision, vision loss, eye pain, muscle weakness, and loss of sensation or coordination. MS takes several forms, with new symptoms either occurring in isolated attacks (relapsing forms) or building up over time (progressive forms). In the relapsing forms of MS, between attacks, symptoms may disappear completely, although some permanent neurological problems often remain, especially as the disease advances. In the progressive forms of MS, bodily function slowly deteriorates and disability worsens once symptoms manifest and will steadily continue to do so if the disease is left untreated.
While the cause is unclear, the underlying mechanism is thought to be either destruction by the immune system or failure of the myelin-producing cells. Proposed causes for this include immune dysregulation, genetics, and environmental factors, such as viral infections. MS is usually diagnosed based on the presenting signs and symptoms and the results of supporting medical tests.
No cure for multiple sclerosis is known. Current treatments are aimed at mitigating inflammation and resulting symptoms from acute flares and prevention of further attacks with disease-modifying medications. Physical therapy and occupational therapy, along with patient-centered symptom management, can help with people's ability to function. The long-term outcome is difficult to predict; better outcomes are more often seen in women, those who develop the disease early in life, those with a relapsing course, and those who initially experienced few attacks.
Multiple sclerosis is the most common immune-mediated disorder affecting the central nervous system. Nearly one million people in the United States had MS in 2022, and in 2020, about 2.8 million people were affected globally, with rates varying widely in different regions and among different populations. The disease usually begins between the ages of 20 and 50 and is twice as common in women as in men. MS was first described in 1868 by French neurologist Jean-Martin Charcot.
The name "multiple sclerosis" is short for multiple cerebro-spinal sclerosis, which refers to the numerous glial scars (or sclerae ¨C essentially plaques or lesions) that develop on the white matter of the brain and spinal cord. Reference Wiki: Multiple sclerosis | Muscular dystrophy (25) Muscular dystrophies (MD) are a genetically and clinically heterogeneous group of rare neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscles over time. The disorders differ as to which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin. Some types are also associated with problems in other organs.
Over 30 different disorders are classified as muscular dystrophies. Of those, Duchenne muscular dystrophy (DMD) accounts for approximately 50% of cases and affects males beginning around the age of four. Other relatively common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, and myotonic dystrophy, whereas limb¨Cgirdle muscular dystrophy and congenital muscular dystrophy are themselves groups of several ¨C usually extremely rare ¨C genetic disorders.
Muscular dystrophies are caused by mutations in genes, usually those involved in making muscle proteins. The muscle protein, dystrophin, is in most muscle cells and works to strengthen the muscle fibers and protect them from injury as muscles contract and relax. It links the muscle membrane to the thin muscular filaments within the cell. Dystrophin is an integral part of the muscular structure. An absence of dystrophin can cause impairments: healthy muscle tissue can be replaced by fibrous tissue and fat, causing an inability to generate force. Respiratory and cardiac complications can occur as well. These mutations are either inherited from parents or may occur spontaneously during early development. Muscular dystrophies may be X-linked recessive, autosomal recessive, or autosomal dominant. Diagnosis often involves blood tests and genetic testing.
There is no cure for any disorder from the muscular dystrophy group. Several drugs designed to address the root cause are currently available including gene therapy (Elevidys), and antisense drugs (Ataluren, Eteplirsen etc.). Other medications used include glucocorticoids (Deflazacort, Vamorolone); calcium channel blockers (Diltiazem); to slow skeletal and cardiac muscle degeneration, anticonvulsants to control seizures and some muscle activity, and Histone deacetylase inhibitors (Givinostat) to delay damage to dying muscle cells. Physical therapy, braces, and corrective surgery may help with some symptoms while assisted ventilation may be required in those with weakness of breathing muscles.
Outcomes depend on the specific type of disorder. Many affected people will eventually become unable to walk and Duchenne muscular dystrophy in particular is associated with shortened life expectancy.
Muscular dystrophy was first described in the 1830s by Charles Bell. The word "dystrophy" comes from the Greek dys, meaning "no, un-" and troph- meaning "nourish".
Reference Wiki: Muscular dystrophy |
Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, drooping eyelids, and difficulties in talking and walking. Onset can be sudden. Those affected often have a large thymus or develop a thymoma.
Myasthenia gravis is an autoimmune disease of the neuromuscular junction which results from antibodies that block or destroy nicotinic acetylcholine receptors (AChR) at the junction between the nerve and muscle. This prevents nerve impulses from triggering muscle contractions. Most cases are due to immunoglobulin G1 (IgG1) and IgG3 antibodies that attack AChR in the postsynaptic membrane, causing complement-mediated damage and muscle weakness. Rarely, an inherited genetic defect in the neuromuscular junction results in a similar condition known as congenital myasthenia. Babies of mothers with myasthenia may have symptoms during their first few months of life, known as neonatal myasthenia. Diagnosis can be supported by blood tests for specific antibodies, the edrophonium test, electromyography (EMG), or a nerve conduction study.
MG is generally treated with medications known as acetylcholinesterase inhibitors, such as neostigmine and pyridostigmine. Immunosuppressants, such as prednisone or azathioprine, may also be used. The surgical removal of the thymus may improve symptoms in certain cases. Plasmapheresis and high-dose intravenous immunoglobulin may be used during sudden flares of the condition. If the breathing muscles become significantly weak, mechanical ventilation may be required. Once intubated acetylcholinesterase inhibitors may be temporarily held to reduce airway secretions.
MG affects 50 to 200 people per million. It is newly diagnosed in 3 to 30 people per million each year. Diagnosis has become more common due to increased awareness. MG most commonly occurs in women under the age of 40 and in men over the age of 60. It is uncommon in children. With treatment, most live to an average life expectancy. The word is from the Greek mys, "muscle" and astheneia "weakness", and the Latin gravis, "serious". Reference Wiki: Myasthenia gravis | Myoclonic dystonia or Myoclonus dystonia syndrome is a rare movement disorder that induces spontaneous muscle contraction causing abnormal posture. The prevalence of myoclonus dystonia has not been reported, however, this disorder falls under the umbrella of movement disorders which affect thousands worldwide. Myoclonus dystonia results from mutations in the SGCE gene coding for an integral membrane protein found in both neurons and muscle fibers. Those suffering from this disease exhibit symptoms of rapid, jerky movements of the upper limbs (myoclonus), as well as distortion of the body's orientation due to simultaneous activation of agonist and antagonist muscles (dystonia).
Myoclonus dystonia is caused by loss-of-function-mutations in the epsilon sarcoglycan gene (SGCE). The disease is dominantly inherited, however SGCE is an imprinted gene, so only the paternal allele is expressed. Therefore, children suffering from this disease inherit the mutation from the father. If the mutated allele is inherited from the mother, the child is not likely to exhibit symptoms.
While no cure has been found for myoclonus dystonia, treatment options are available to those suffering from the disease. Ethanol often ameliorates the symptoms well, and so the syndrome is also called "Alcohol-responsive dystonia". Alcohol may be substituted by benzodiazepines, such as clonazepam, which work through the same mechanism. Deep brain stimulation (DBS) is another viable option that can alleviate symptoms without the unwanted side effects of medications, and has been successful in treating other movement disorders. Reference Wiki: Myoclonic dystonia | In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease (Greek : myo- muscle + patheia -pathy : suffering). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("neuropathies" or "neurogenic" disorders) or elsewhere (e.g., the brain).
This muscular defect typically results in myalgia (muscle pain), muscle weakness (reduced muscle force), or premature muscle fatigue (initially normal, but declining muscle force). Muscle cramps, stiffness, spasm, and contracture can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as muscle atrophy (abnormally small) or a pseudoathletic appearance (abnormally large).
Capture myopathy can occur in wild or captive animals, such as deer and kangaroos, and leads to morbidity and mortality. It usually occurs as a result of stress and physical exertion during capture and restraint.
Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Some conditions, such as myositis, can be considered both neuromuscular and musculoskeletal. Different myopathies may be inherited, infectious, non-communicable, or idiopathic (cause unknown). The disease may be isolated to affecting only muscle (pure myopathy), or may be part of a systemic disease as is typical in mitochondrial myopathies. Reference Wiki: Myofibrillar myopathy |
Myoglobinuria (1) Myoglobinuria is the presence of myoglobin in the urine, which usually results from rhabdomyolysis or muscle injury. Myoglobin is present in muscle cells as a reserve of oxygen. Reference Wiki: Myoglobinuria | Myopathy (25) In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy means muscle disease (Greek : myo- muscle + patheia -pathy : suffering). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("neuropathies" or "neurogenic" disorders) or elsewhere (e.g., the brain).
This muscular defect typically results in myalgia (muscle pain), muscle weakness (reduced muscle force), or premature muscle fatigue (initially normal, but declining muscle force). Muscle cramps, stiffness, spasm, and contracture can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as muscle atrophy (abnormally small) or a pseudoathletic appearance (abnormally large).
Capture myopathy can occur in wild or captive animals, such as deer and kangaroos, and leads to morbidity and mortality. It usually occurs as a result of stress and physical exertion during capture and restraint.
Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Some conditions, such as myositis, can be considered both neuromuscular and musculoskeletal. Different myopathies may be inherited, infectious, non-communicable, or idiopathic (cause unknown). The disease may be isolated to affecting only muscle (pure myopathy), or may be part of a systemic disease as is typical in mitochondrial myopathies. Reference Wiki: Myopathy | Myosclerosis (1) In myosclerosis, the muscle is infiltrated with connective tissue and fibrosis, having a firm, "woody" feel upon palpitation, with the muscles appearing slender. Reference Wiki: Myosclerosis |
Autosomal dominant myosin storage congenital myopathy-7A (CMYP7A) is a skeletal muscle disorder with wide phenotypic variability. The age at symptom onset can range from early childhood to late adulthood. Affected individuals have proximal muscle weakness affecting the upper and lower limbs and distal muscle weakness of the lower limbs, resulting in gait difficulties and scapular winging (scapuloperoneal myopathy). Additional features may include thin habitus, high-arched palate, foot drop, pes cavus, calf pseudohypertrophy, and decreased reflexes. The severity is also variable: some patients develop respiratory insufficiency, joint contractures, and scoliosis in the first decades, whereas others are clinically unaffected, but show subtle signs of the disorder on examination. Serum creatine kinase may be normal or elevated. The disease is usually slowly progressive and most patients remain ambulatory. Skeletal muscle biopsy can show different abnormalities, including hyaline bodies, type 1 fiber predominance, congenital fiber-type disproportion (CFTD), and nonspecific myopathic changes with myofibrillar disarray. Intrafamilial variability is common (Dye et al., 2006; Pegoraro et al., 2007; review by Tajsharghi and Oldfors, 2013). Reference OMIM: Myosin storage myopathy | Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness. In DM, muscles are often unable to relax after contraction. Other manifestations may include cataracts, intellectual disability and heart conduction problems. In men, there may be early balding and infertility. While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s.
Myotonic dystrophy is caused by a genetic mutation in one of two genes. Mutation of the DMPK gene causes myotonic dystrophy type 1 (DM1). Mutation of CNBP gene causes type 2 (DM2). DM is typically inherited, following an autosomal dominant inheritance pattern, and it generally worsens with each generation. A type of DM1 may be apparent at birth. DM2 is generally milder. Diagnosis is confirmed by genetic testing.
There is no cure. Treatments may include braces or wheelchairs, pacemakers and non-invasive positive pressure ventilation. The medications mexiletine or carbamazepine can help relax muscles. Pain, if it occurs, may be treated with tricyclic antidepressants and nonsteroidal anti-inflammatory drugs (NSAIDs).
Myotonic dystrophy affects about 1 in 2,100 people, a number that was long estimated to be much lower (often cited as 1 in 8,000), reflecting that not all patients have immediate symptoms and, once they do have symptoms, the long time it typically takes to get to the right diagnosis. It is the most common form of muscular dystrophy that begins in adulthood. It was first described in 1909, with the underlying cause of type 1 determined in 1992. Reference Wiki: Myotonic dystrophy Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness.[1] In DM, muscles are often unable to relax after contraction.[1] Other manifestations may include cataracts, intellectual disability and heart conduction problems.[1][2] In men, there may be early balding and infertility.[1] While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s.[1] Reference Wiki: Myotonic dystrophy | Myotonic dystrophy (DM) is a type of muscular dystrophy, a group of genetic disorders that cause progressive muscle loss and weakness. In DM, muscles are often unable to relax after contraction. Other manifestations may include cataracts, intellectual disability and heart conduction problems. In men, there may be early balding and infertility. While myotonic dystrophy can occur at any age, onset is typically in the 20s and 30s.
Myotonic dystrophy is caused by a genetic mutation in one of two genes. Mutation of the DMPK gene causes myotonic dystrophy type 1 (DM1). Mutation of CNBP gene causes type 2 (DM2). DM is typically inherited, following an autosomal dominant inheritance pattern, and it generally worsens with each generation. A type of DM1 may be apparent at birth. DM2 is generally milder. Diagnosis is confirmed by genetic testing.
There is no cure. Treatments may include braces or wheelchairs, pacemakers and non-invasive positive pressure ventilation. The medications mexiletine or carbamazepine can help relax muscles. Pain, if it occurs, may be treated with tricyclic antidepressants and nonsteroidal anti-inflammatory drugs (NSAIDs).
Myotonic dystrophy affects about 1 in 2,100 people, a number that was long estimated to be much lower (often cited as 1 in 8,000), reflecting that not all patients have immediate symptoms and, once they do have symptoms, the long time it typically takes to get to the right diagnosis. It is the most common form of muscular dystrophy that begins in adulthood. It was first described in 1909, with the underlying cause of type 1 determined in 1992. Reference Wiki: Myotonic muscular dystrophy |
Neutral lipid storage disease (also known as Chanarin¨CDorfman syndrome) is a congenital autosomal recessive disorder characterized by accumulation of triglycerides in the cytoplasm of leukocytes (Jordans' anomaly), muscle, liver, fibroblasts, and other tissues. It commonly occurs as one of two subtypes, cardiomyopathic neutral lipid storage disease (NLSD-M), or ichthyotic neutral lipid storage disease (NLSD-I) which is also known as Chanarin¨CDorfman syndrome), which are characterized primarily by myopathy and ichthyosis, respectively. Normally, the ichthyosis that is present is typically non-bullous congenital ichthyosiform erythroderma which appears as white scaling.
It has been associated genetically with mutations in the CGI-58 gene (for NLSD-I) or the ATGL/PNPLA2 gene (for NLSD-M). Reference Wiki: Neutral lipid storage myopathy | X-linked dystonia parkinsonism (XDP), also known as lubag syndrome or X-linked dystonia of Panay, is a rare X-linked progressive movement disorder with high penetrance found almost exclusively in males from Panay. It is characterized by dystonic movements first typically occurring in the 3rd and 4th decade of life. The dystonic movements often either coexist or develop into parkinsonism within 10 years of disease onset. Reference Wiki: Parkinsonism-dystonia | A dystonia characterized by epilepsy and attacks of dystonic or choreathetotic movements, which may coexist or occur singly, that has_material_basis_in heterozygous mutation in the KCNMA1 gene on chromosome 10q22. Reference DiseaseOntology: paroxysmal nonkinesigenic dyskinesia 3 |
Progressive external ophthalmoplegia is characterized by multiple mitochondrial DNA deletions in skeletal muscle. The most common clinical features include adult onset of weakness of the external eye muscles and exercise intolerance. Additional symptoms are variable, and may include cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism, and parkinsonism. Both autosomal dominant and autosomal recessive inheritance can occur; autosomal recessive inheritance is usually more severe (Filosto et al., 2003; Luoma et al., 2004). Reference OMIM: Progressive external ophthalmoplegia | Reducing-body myopathy (RBM) is a rare myopathy characterized pathologically by the presence of intracytoplasmic inclusion bodies strongly stained by menadione-linked alpha-glycerophosphate dehydrogenase (MAG) in the absence of substrate, alpha-glycerophosphate. The term 'reducing body' refers to the reducing activity of the inclusions to nitroblue tetrazolium (NBT) in the absence of substrate. This condition is also commonly associated with rimmed vacuoles and cytoplasmic bodies. The clinical features of RBM are variable; a severe form has onset in infancy or early childhood and results in severe disability or early death, and a less severe form has onset in late childhood or adulthood (RBMX1B; 300718) (summary by Liewluck et al., 2007 and Shalaby et al., 2009). Reference OMIM: Reducing body myopathy | Rhabdomyosarcoma (5) Rhabdomyosarcoma (RMS) is a highly aggressive form of cancer that develops from mesenchymal cells that have failed to fully differentiate into myocytes of skeletal muscle. Cells of the tumor are identified as rhabdomyoblasts.
The four subtypes are embryonal rhabdomyosarcoma, alveolar rhabdomyosarcoma, pleomorphic rhabdomyosarcoma, and spindle-cell/sclerosing rhabdomyosarcoma. Embryonal and alveolar are the main groups, and these types are the most common soft tissue sarcomas of childhood and adolescence. The pleomorphic type is usually found in adults.
It is generally considered to be a disease of childhood, as the vast majority of cases occur in those below the age of 18. It is commonly described as one of the small-blue-round-cell tumors of childhood due to its appearance on an H&E stain. Despite being relatively rare, it accounts for approximately 40% of all recorded soft-tissue sarcomas.
RMS can occur in any soft-tissue site in the body, but is primarily found in the head, neck, orbit, genitourinary tract, genitals, and extremities. No clear risk factors have been identified, but the disease has been associated with some congenital abnormalities. Signs and symptoms vary according to tumor site, and prognosis is closely tied to the location of the primary tumor. Common sites of metastasis include the lungs, bone marrow, and bones. There are many classification systems for RMS and a variety of defined histological types. Embryonal rhabdomyosarcoma is the most common type and comprises about 60% of cases.
Outcomes vary considerably, with five-year survival rates between 35 and 95%, depending on the type of RMS involved, so clear diagnosis is critical for effective treatment and management.
Treatment usually involves a combination of surgery, chemotherapy, and radiation. 60 to 70% of newly diagnosed patients with nonmetastatic disease can be cured using this combined approach to therapy. Despite aggressive multimodality treatment, less than 20% of patients with metastatic RMS are able to be cured of their disease.
Reference Wiki: Rhabdomyosarcoma |
A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glucose breakdown, typically in muscles and/or liver cells.[1] Reference Wiki: Rippling muscle disease | A disease of mental health involving the abuse or dependence on a substance that is ingested in order to produce a high, alter one's senses, or otherwise affect functioning. Reference DiseaseOntology: RYR1-related disorders | A muscular dystrophy which begins at the lower legs and affects the shoulder region earlier and more severely than distal arm. Reference DiseaseOntology: Scapuloperoneal myopathy |
Spinal and bulbar muscular atrophy (SBMA), popularly known as Kennedy's disease, is a rare, adult-onset, X-linked recessive lower motor neuron disease caused by trinucleotide CAG repeat expansions in exon 1 of the androgen receptor (AR) gene, which results in both loss of AR function and toxic gain of function.[2][3] Reference Wiki: Spinal and bulbar muscular atrophy | Inclusion body myositis (IBM) () (sometimes called sporadic inclusion body myositis, sIBM) is the most common inflammatory muscle disease in older adults. The disease is characterized by slowly progressive weakness and wasting of both proximal muscles (located on or close to the torso) and distal muscles (close to hands or feet), most apparent in the finger flexors and knee extensors. IBM is often confused with an entirely different class of diseases, called hereditary inclusion body myopathies (hIBM). The "M" in hIBM is an abbreviation for "myopathy" while the "M" in IBM is for "myositis". In IBM, two processes appear to occur in the muscles in parallel, one autoimmune and the other degenerative. Inflammation is evident from the invasion of muscle fibers by immune cells. Degeneration is characterized by the appearance of holes, deposits of abnormal proteins, and filamentous inclusions in the muscle fibers. sIBM is a rare disease, with a prevalence ranging from 1 to 71 individuals per million.
Weakness comes on slowly (over months to years) in an asymmetric manner and progresses steadily, leading to severe weakness and wasting of arm and leg muscles. IBM is more common in men than women. Patients may become unable to perform activities of daily living and most require assistive devices within 5 to 10 years of symptom onset. sIBM does not significantly affect life expectancy, although death related to malnutrition and respiratory failure can occur. The risk of serious injury due to falls is increased. There is no effective treatment for the disease as of 2019. Reference Wiki: Sporadic inclusion body myositis | Ullrich congenital muscular dystrophy (UCMD) is a form of congenital muscular dystrophy. There are two forms: UCMD1 and UCMD2.
UCMD1 is associated with variants of type VI collagen, while UCMD2 is associated with variants of type XII collagen.
UCMD is commonly associated with contractures, joint laxity, muscle weakness and respiratory problems, though cardiac issues are not associated with this type of CMD. It is named after Otto Ullrich, who is also known for the Ullrich-Turner syndrome. Reference Wiki: Ullrich congenital muscular dystrophy |
Familial visceral myopathy (VSCM) is a rare inherited form of myopathic pseudoobstruction, characterized by impaired function of enteric smooth muscle cells resulting in abnormal intestinal mobility, severe abdominal pain, malnutrition, and even death (Lehtonen et al., 2012). Visceral myopathy represents a phenotypic spectrum of disease characterized by inter- and intrafamilial variability, in which the most severely affected patients exhibit prenatal bladder enlargement, intestinal malrotation, neonatal functional gastrointestinal obstruction, and chronic dependence on total parenteral nutrition (TPN) and urinary catheterization (summary by Wangler et al., 2014). Reference OMIM: Visceral myopathy | Distal myopathy is a group of rare genetic disorders that cause muscle damage and weakness, predominantly in the hands and/or feet. Mutation of many different genes can be causative. Many types involve dysferlin.[1] Reference Wiki: Welander distal myopathy |
