OBJECTIVETo report on two cases affected with immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX).

METHODSTwo unrelated Chinese infants affected with IPEX were investigated. Case 1 was a 4-month-old boy with neonatal diabetes and severe enteropathy. Case 2 was a 6-day newborn boy with neonatal diabetes and ketoacidosis. DNA samples of the two infants and their parents were sequenced for FOXP3 gene mutations. Suspected mutations were verified among 100 unrelated healthy controls. The function of mutations was predicted with bioinformatics software.

RESULTSBoth infants had onset of the disease during neonatal period, and manifested insulin-dependent diabetes mellitus, persistent diarrhea, eczema and malnutrition. In case 1, a novel splice site mutation was identified in intron 9 (c.967+3A>T) of the FOXP3 gene, for which his mother was a carrier. For case 2, a missense mutation (c.1150G>A) was detected in exon 11 of the FOXP3 gene, for which his mother was also a carrier. The IVS9 c.967+3A mutation was not detected among the 100 healthy controls. As predicted with Human Splicing Finder software, the c.967+3A>T mutation may influence the splicing of mRNA and affect the function of protein.

CONCLUSIONBoth cases had typical clinical manifestation of the IPEX syndrome, among whom a novel splice site mutation (IVS9 c.967+3A>T) and a missense mutation (c.1150G>A) of the FOXP3 gene were identified. The clinical manifestation of the IPEX syndrome may be variable and the mortality is high. FOXP3 gene sequencing is recommended when insulin-dependent diabetes mellitus is diagnosed during the neonatal period.