ATM and Immunodeficiency: Syndromic combined immunodeficiencies are characterized by mutations in genes such as STAT3, DOCK8, ATM, WAS, and TBX1, including the dominant-negative STAT3 variant (c.1144C>T, p.Arg382Trp) and the X-linked WAS mutation (c.271C>T), both recognized as established causes of hyper-IgE syndrome and WAS, respectively [5,29,39].