Clinical and molecular characteristics of immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome in China.

Immunodysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare X-linked recessive disorder causing life-threatening systemic autoimmunity because of immunodysregulation. The FOXP3 gene had been reported as the responsible gene, which was critical for the functions of CD4(+) CD25(+) FOXP3(+) regulatory T cells (Tregs) and maintenance of peripheral immunologic tolerance. So far, no IPEX patients with definite mutations in the FOXP3 gene had been reported in China. In this study, the genotypes and phenotypes were investigated in three IPEX infants from three unrelated Chinese families. Patient 1 (P1) presented with a classical clinical phenotype, whose mutation was a novel frameshift insertion in exon 11, led to the complete abrogation of Tregs. Patient 2 (P2) showed incomplete IPEX phenotype. He carried a missense mutation in exon 11 with slightly increased frequency of Tregs, whereas Patient 3 (P3) presented with a relatively mild classical phenotype and had a previously reported missense mutation in exon 10 with decreased frequency of Tregs. We firstly report three Chinese IPEX patients with definite mutations of FOXP3 gene. Our study indicated the potential correlation between the genotype and the phenotype of IPEX, which was different from the previous reports.