Pedigree, validation of the WAS variant, and electron microscopy of platelets. (A) Pedigree of the family. Generations are designated by Roman and subjects by Arabic numerals. Squares and circles represent male and female subjects, respectively. Solid (black) symbols indicate patients, while open (white) symbols indicate unaffected family members. Individuals labeled with a star (II.3, III.4, III.5, IV.2, and IV.3) were subjected to exome sequencing. (B) Sanger sequencing and intrafamilial segregation pattern of the c.881T>C WAS variant. The genotypes of the different family members are indicated between parentheses. The arrow indicates the position of the variant. The reference sequences are presented in color. The alternative alleles observed in each individual are shown above (Y: C or T; dots: identical to reference sequence). (C) Transmission electron microscopy images showing the ultrastructure of platelets from a healthy donor (a,b) and subject III.4 (c-g). Wide-field electron micrographs of platelets show the increased platelet size and heterogeneous content in subject III.4 (c) compared with control platelets (a). The arrow points to a platelet with high content and the arrowhead to a platelet with low content (e). Higher magnifications are shown to illustrate the compact appearance (d,f) and gray appearance (g) of the platelets. α, α granules; δ, dense granules; ocs, open canalicular system.