摘要

Severe combined immunodeficiency (SCID) is the most serious disorder among primary immunodeficiency diseases threatening children's life. Atypical SCID variant, presenting with mild reduced T cells subsets, is often associated with infection susceptibility but poor clinical diagnosis. The atypical X-SCID patient in the present study showed a mild clinical presentation with a (TNK+B+)-N-low immunophenotype. The patient has reduced T- cell subpopulations with a subdued thymic output measured by sjTRECs. Further analysis showed that T cells maintained a normal proliferation and a broad V beta repertoire. NK cells, however, exhibited a skewed development toward immature CD3(-)CD16(+)CD56(-) cells. Genetic analysis revealed a novel deletion at nucleotide 52 in exon 1 of IL2RG gene. Sequence alignment predicted a truncated IL2RG protein missing signal peptide derived from a possible alternative reading frame. The novel mutation in IL2RG gene identified in our study may help the early diagnosis of atypical X-SCID.