FADD and chronic granulomatous disease: Sixteen cases (45.7%) were confirmed to have PID, including SCID (7 cases, 20.0%), chronic granulomatous disease (6 cases, 17.1%), Mendelian susceptibility to mycobacterial disease (2 cases, 5.7%), and fas associated via death domain (FADD) gene mutation (1 case, 2.6%).