Identification of a pathogenic TUBB1 variant in a Chinese family with congenital macrothrombocytopenia through whole genome sequencing.

Congenital macrothrombocytopenia is a genetically heterogeneous group of rare disorders. We herein report a large Chinese family presented with phenotypic variability involving thrombocytopenia and/or giant platelets. Whole genome sequencing (WGS) of the proband and one of his affected brothers identified a potentially pathogenic c.952 C > T heterozygous variant in the TUBB1 gene. This p.R318W β1-tubulin variant was also identified in three additional siblings and five members of the next generation. These findings were consistent with an autosomal dominant inheritance with incomplete penetrance. Moreover, impaired platelet agglutination in response to ristocetin was detected in the patient's brother. Half of the family members harboring the p.R318W mutation displayed significantly decreased external release of p-selectin by stimulated platelets. The p.R318W β1-tubulin mutation was identified for the first time in a Chinese family with congenital macrothrombocytopenia using WGS as an unbiased sequencing approach. Affected individuals within the family demonstrated impaired platelet aggregation and/or release functions.