Platelet-type bleeding disorder 15

Any inherited bleeding disorder, platelet-type in which the cause of the disease is a mutation in the ACTN1 gene, characterized by mild thrombocytopenia, enlarged platelets, and platelet anisocytosis, with most individuals exhibiting no bleeding or only mild epistaxis. Human platelet studies show normal aggregation, clot retraction, and spreading, indicating that bleeding symptoms arise from reduced platelet mass rather than functional defects. Missense variants in ACTN1 disrupt actin-filament organization in megakaryocytes, producing fewer and larger proplatelet tips and resulting in macrothrombocytopenia.