A blood platelet disease characterized by selective deficiency in the number and contents of platelet alpha-granules, macrothrombocytopenia, enlarged platelets, myelofibrosis, splenomegaly, and increased bleeding time that has_material_basis_in homozygous or compound heterozygous mutation in the NBEAL2 gene on chromosome 3p21.

Reference
DiseaseOntology: Gray platelet syndrome