The patients with ATM predominantly presented ataxia/telangiectasia (46.2%) and infections (32.1%), while allergy (52.6%) and infection (94.4%) were the dominant first manifestations in STAT3 (AD-LOF) and DNMT3B/ZBTB24 mutations, respectively. The gene discussed is DNMT3B; the disease is Ataxia-telangiectasia.