Nonmuscle myosin heavy chain IIA mutations define a spectrum of autosomal dominant macrothrombocytopenias: May-hegglin anomaly and Fechtner, Sebastian, Epstein, and alport-like syndromes

Abstract

May-Hegglin anomaly (MHA) and Fechtner (FTNS) and Sebastian (SBS) syndromes are autosomal dominant platelet disorders that share macrothrombocytopenia and characteristic leukocyte inclusions. FTNS has the additional clinical features of nephritis, deafness, and cataracts. Previously, mutations in the nonmuscle myosin heavy chain 9 gene (MYH9), which encodes nonmuscle myosin heavy chain IIA (MYHIIA), were identified in all three disorders. The spectrum of mutations and the genotype-phenotype and structure-function relationships in a large cohort of affected individuals (n = 27) has now been examined. Moreover, it is demonstrated that MYH9 mutations also result in two other FTNS-like macrothro..