The study aims to describe the clinical manifestations, immunophenotype, and gene mutation characteristics of a child with X-linked severe combined immunodeficiency (X-SCID) caused by an IL2RG mutation (NM_000206.3; exon 2 c.216C > A, p.Cys72*), and to contextualize these findings through a review of reported cases of X-SCID associated with Talaromyces marneffei (T. marneffei) infection, highlighting the immunological and diagnostic relevance of the mutation. The gene discussed is IL2RG; the disease is severe combined immunodeficiency.