Variants in genes encoding components of NOX enzymes including NOX1, NOX2 and DUOX2 confer susceptibility to VEO-IBD (152, 245–248), while NOX2 complex variants associated with CGD due to absent or minimal output of superoxide manifest in 40-50% of CGD patients as CGD-associated IBD. This evidence concerns the gene DUOX2 and chronic granulomatous disease.