NBEAL2 (neurobeachin like 2) is a 300 kDa BEACH domain-containing scaffolding protein essential for alpha-granule biogenesis and immune cell function. Functionally, NBEAL2 facilitates alpha-granule cargo retention in platelets 1 and plays critical roles in neutrophil and NK cell granule formation and secretion 2. The protein works through multiple protein-protein interactions; it associates with Dock7, Sec16a, and Vac14 3, and regulates CTLA-4 trafficking in conventional T cells 4 and RPS6 protein homeostasis in mast cells 5. Recessive loss-of-function mutations in NBEAL2 cause gray platelet syndrome (GPS) 6, characterized by macrothrombocytopenia, alpha-granule-deficient platelets, myelofibrosis, and impaired hemostatic function. Beyond platelet defects, GPS patients exhibit increased infection susceptibility due to neutrophil and NK cell dysfunction 2. Notably, some GPS patients develop autoimmunity through reduced CTLA-4 expression in effector T cells, suggesting NBEAL2's broader immunoregulatory role 4. NBEAL2 inactivation also causes mast cell abnormalities including altered drug transporter localization and pro-inflammatory phenotypes 57. These findings position NBEAL2 as a critical regulator of both hemostasis and immune homeostasis, with potential therapeutic implications for autoimmune complications in GPS patients 8.