Family pedigrees and location of the β1-tubulin variants. (A) Pedigrees of the affected families with inherited thrombocytopenia. The index cases are indicated with black arrows. The upper right quarter red shading in symbols indicates individuals with thrombocytopenia, lower right quarter green shading denotes increased MPV, and upper and lower left quarter blue shading indicates heterozygous or homozygous for TUBB1 variant. NA, not available for the study; unlabeled symbols correspond to nonblood relatives not included in the study. (B) Representative peripheral blood smears from pedigree I after May-Grünwald Giemsa staining (×100). Variable platelet size was observed with large (arrows) and giant (cross) platelets. (C) Schematic representation of the β1-tubulin protein with all the reported variants. Variants in pedigrees reported in the present study are highlighted in bold; underlined variant is novel and the one within blue rectangle was found in homozygosity. (D) Structural analysis of the p.Gly109Glu missense variant using a β1-tubulin 3D model (software https://www3.cmbi.umcn.nl/hope/). The protein is colored in gray; the side chains of both the wild-type and the mutant residues are shown in green and red, respectively.