PRKACG encodes the γ-catalytic subunit of cAMP-dependent protein kinase (PKA), a serine/threonine kinase expressed primarily in testis 1. As a PKA catalytic subunit, PRKACG phosphorylates numerous cytoplasmic and nuclear substrates in response to cAMP signaling 2. The protein is localized to chromosome 9 1. PRKACG plays a critical role in platelet biogenesis and function. Loss-of-function mutations impair proplatelet formation in megakaryocytes and reduce filamin A levels, leading to severe macrothrombocytopenia with giant platelets and bleeding tendency 3. A missense mutation (p.74Ile>Met) was identified as causative for inherited macrothrombocytopenia with thrombocytopathy, where platelet activation and cytoskeleton reorganization were markedly impaired 3. Overexpression of wild-type PRKACG rescued defective proplatelet formation in patient megakaryocytes, establishing PRKACG as central to platelet biogenesis 3. Clinically, PRKACG mutations constitute a newly recognized genetic cause of inherited platelet disorders 45. PRKACG is designated as the causative gene for Bleeding disorder, platelet-type, 19 6. Additionally, PRKACG expression associates with HDL metabolism in coronary artery disease patients 7, and genetic variants influence vitamin D status 8, suggesting broader metabolic functions beyond platelet biology.