A and B, Picture (Fig 1, A) and pedigree (Fig 1, B) of 4 patients showing a de novo monoallelic mutation in CDC42. The affected subjects are indicated as follows: circles, female subjects; squares, male subjects. WT, Wild-type. C and D, Crystal structure of CDC42 (orange). Highlighted are the Wiskott-Aldrich syndrome protein (WASP) binding domain (Fig 1, C) and the 3 reported C-terminal variants (Fig 1, D). Laboratory parameters measured were CRP, ESR, ferritin, hemoglobin, platelet, and cytokines (IL-18, IL-18BP, and CXCL9).