Gray platelet syndrome

Gray platelet syndrome (GPS), or platelet alpha-granule deficiency, is a rare congenital bleeding disorder caused by a reduction or absence of alpha-granules in blood platelets, and the release of proteins normally contained in these granules into the marrow, causing myelofibrosis.

GPS is primarily inherited in an autosomal recessive manner, and the gene that is mutated in GPS has recently been mapped to chromosome 3p and identified as NBEAL2. NBEAL2 encodes a protein containing a BEACH domain that is predicted to be involved in vesicular trafficking. It is expressed in platelets and megakaryocytes and is required for the development of platelet alpha-granules. NBEAL2 expression is also required for the development of thrombocytes in zebrafish.