NBEAL2 expression is also required for the development of thrombocytes in zebrafish.In Japan, GPS was found in 24 affected patients in a single family. There was at least 1 instance of male-to-male transmission, consistent with autosomal dominant inheritance.A study reported of 14 families with GPS, 11 families had clear autosomal recessive inheritance. This was evidenced by consanguinity or multiple affected siblings with unaffected parents. The families had various backgrounds, including Bedouin, Turkish, Mennonite, French, German, Somali, African American, and mixed Northern and Southern European.GPS is characterized by "thrombocytopenia, and abnormally large agranular platelets in peripheral blood smears." The defect in GPS is the failure of megakaryocytes to package secretory proteins into alpha-granules. Patients with the GPS are affected by mild to moderate bleeding tendencies. Usually these are not major bleeds but there has been some life-threatening cases. Affected women will tend to have heavy, irregular periods. Myelofibrosis is a condition that usually comes with GPS. Diagnosis
GPS is diagnosed based on clinical findings and requires demonstration of absence or marked reduction of alpha-granules by electron microscopy (EM). High serum vitamin B12 levels are common in patients diagnosed with GPS. Bone marrow sampling, though not required for diagnosis of GPS, might be necessary to evaluate myelofibrosis occurring in GPS and to exclude other disorders. Management
There is no specific treatment  for GPS, but it can be managed by anticipating and preventing the risks of bleeding. The treatment options include desmopressin. Splenectomy can be used to increase the platelet counts in those whose platelet counts decrease to approximately 30,000/microliter.
"Avapritinib: A Selective Inhibitor of KIT and PDGFRα that Reverses ABCB1 and ABCG2-Mediated Multidrug Resistance in Cancer Cell Lines". Mol. Pharm. 16 (7): 3040–3052. doi:10.1021/acs.molpharmaceut.9b00274. PMC 6620786. PMID 31117741. Gebreyohannes YK, Wozniak A, Zhai ME,  et al. (January 2019). "Robust Activity of Avapritinib, Potent and Highly Selective Inhibitor of Mutated KIT, in Patient-derived Xenograft Models of Gastrointestinal Stromal Tumors". Clin. Cancer Res. 25 (2): 609–618. doi:10.1158/1078-0432.CCR-18-1858. PMID 30274985. External links
"Avapritinib". Drug Information Portal. U.S. National Library of Medicine (NLM). "Avapritinib". NCI Dictionary of Cancer Terms. National Cancer Institute. "Avapritinib". National Cancer Institute. 28 January 2020. Clinical trial number NCT02508532 for "(NAVIGATOR) Study of BLU-285 in Patients With Gastrointestinal Stromal Tumors (GIST) and Other Relapsed and Refractory Solid Tumors" at ClinicalTrials.gov
Clinical trial number NCT02561988 for "(EXPLORER) Study of BLU-285 in Patients With Advanced Systemic Mastocytosis (AdvSM) and Relapsed or Refractory Myeloid Malignancies" at ClinicalTrials.gov
Clinical trial number NCT03580655 for "(PATHFINDER) Study to Evaluate Efficacy and Safety of Avapritinib (BLU-285), A Selective KIT Mutation-targeted Tyrosine Kinase Inhibitor, in Patients With Advanced Systemic Mastocytosis" at ClinicalTrials.gov