IL2RG and severe combined immunodeficiency: A comprehensive search was conducted in PubMed, Web of Science, ClinVar, Embase, and Medline databases using the search terms “IL2RG,” “BCG disease,” and “SCID.” This search yielded 11 reports and 24 children of X-SCID complicated with BCG disease caused by IL2RG gene mutation, published prior to June 2024 (Table 2).