Clinical characteristics and mutation analysis of X-linked severe combined immunodeficiency in China

X-linked severe combined immunodeficiency (X-SCID) is a rare, life-threatening immune disorder, caused by mutations of the gene for the γ-chain (γc) of the interleukin-2 receptor, IL2RG. We analyzed the clinical, immunologic, and molecular characteristics of children with X-SCID, attempting to improve the diagnosis and treatment of X-SCID in China.

X-SCID was suspected in male infants with recurrent or persistent infections. Eleven male infants from ten unrelated Chinese families were included. The IL2RG gene was amplified and sequenced, followed by mutation analysis in these children and their female relatives. X-linked short tandem repeat (X-STR) typing was done to define the maternal lymphocyte engraftment.

The 11 children exhibited recurrent infections and 10 of them had lymphopenia. B cells were present in all patients, T cells were markedly reduced in 10, and NK cells were markedly reduced in 9. Nine IL2RG gene mutations were identified in the 11 children, with 5 novel mutations. One patient was found to have the maternal lymphocyte engraftment.

The clinical presentations and immunologic characteristics of the X-SCID patients were accordingly quite uniform despite the heterogeneity of mutations locating almost in the entire γc gene.