Novel genetic duplication in XIAP leading to absence of protein and function. (A) Genome sequencing read mapping alignment data from proband revealing intragenic multiexonic duplication in the XIAP gene (NM_001167.4). (B) Western blotting analysis of PBMC from the proband, his mother, his father, and maternal grandfather with anti-XIAP and anti-GAPDH (loading control). (C) PBMC from the proband, his mother, and his father were stimulated with media alone (unstimulated), muramyl dipeptide or LPS and intracellular cytokine production was measured using anti-TNFα. Plots are gated on HLA-DR–positive, CD14-positive monocytes. Western blots and flow cytometry plots are representative of 2 independent experiments.