Association study between the IL4, IL13, IRF1 and UGRP1 genes in chromosomal 5q31 region and Chinese Graves' disease.

Graves' disease (GD) was believed to be a polygenic disease. Several chromosomal regions were linked to GD, and the 5q31 chromosome regions containing several interleukin genes cluster were worth observing. In this study, IL4, IL13, IRF1 and UGRP1 genes were sequenced, and 5, 3, 7 and 7 polymorphisms respectively were discovered. Then an extended association study for the attracting polymorphisms was performed with 146 sporadic Graves' patients, 142 unrelated controls and the 54 multiplex Graves' families. However, the genotype and allele frequency distribution of these polymorphisms had similar distribution between the Graves' patients and unrelated controls, and transmission disequilibrium tests indicated that none of them showed dominant transmission from heterozygous parents to the affected offsprings. Comparison of the clinical variables of the Graves' patients indicated that the onset ages of the patients carrying TT at IRF1 6477 T/G locus were younger than those having variant allele (TG, GG); the difference was of statistical significance (P=0.005, Pc=0.020). Our association study revealed that, IL4, IL13, IRF1 and UGRP1 genes in chromosomal 5q31 regions might not confer susceptibility to Chinese GD. But those individuals who were TT homozygous at IRF1 6477 T/G locus seemed to be attacked by GD much earlier than others.