TPM4-related platelet disorder

A platelet disorder in which the cause of the disease is a variant in the TPM4 gene which encodes tropomyosin‑4, a key actin‑binding protein required for cytoskeletal stability during megakaryocyte maturation and platelet formation. Affected individuals show macrothrombocytopenia or normal platelet counts with enlarged platelets, often accompanied by variable platelet functional defects including impaired spreading on fibrinogen, reduced formation of filopodia and lamellipodia, decreased granule content, and vacuolated platelets. Clinical manifestations include easy bruising, epistaxis, gum bleeding, menorrhagia, and bleeding after surgery or tooth extraction; however, some mutation carriers are minimally symptomatic or asymptomatic.