Correlation between DQB1 genetic polymorphism and genetic susceptibility in patients diagnosed with irritable bowel syndrome with diarrhea.

We examined patients of Han nationality diagnosed with irritable bowel syndrome with diarrhea (IBS-D) in Guangdong, China, to analyze the correlation between DQB1 allele polymorphisms and the genetic susceptibility to IBS-D. A total of 120 IBS-D patients of Han nationality in Guangdong, China, and 60 healthy control volunteers were included. DQB1 allele polymorphisms were investigated by polymerase chain reaction. Subjects' serum interleukin (IL)-10 level, colonic permeability, and tight junction marker zonula occludens 1 (ZO1) mRNA level were also investigated. Our data showed that the DQB1*02 allele frequency was significantly higher in IBS-D patients, while the DQB1*0603 frequency was lower than in healthy volunteers. The DQB1*03, DQB1*04, DQB1*05, DQB1*0601, DQB1*0602, and DQB1*0604 alleles did not show significant differences between IBS-D patients and healthy controls. Furthermore, patients with DQB1*03- positive and DQB1*0603-negative alleles showed more severe colonic permeability and lower serum IL-10 level and ZO1 level compared to healthy controls or even IBS-D patients with other genotypes. The present study indicated the DQB1*02 or DQB1*0603 alleles are related to IBS-D occurrence in Guangdong, China, and the mechanism of the disease may be related to reduced serum IL-10 levels.