Macrothrombocytopenia, isolated, 1, autosomal dominant

Any autosomal dominant macrothrombocytopenia in which the cause of the disease is a mutation in the TUBB1 gene, characterized by mild to moderate thrombocytopenia with large platelets and normal or near-normal bleeding symptoms. Structural studies in patient platelets show disorganized or reduced beta1-tubulin staining and abnormal marginal microtubule bands, impairing proplatelet formation and leading to fewer, larger circulating platelets. Functional platelet assays in affected individuals typically show qualitatively normal aggregation, with the clinical phenotype driven primarily by reduced platelet number rather than intrinsic platelet-function defects.