Association between HLA-DQB1 alleles and type 1 diabetes in a case-parentsstudy conducted in Santiago, Chile

The human leukocyte antigen (HLA) system plays a crucial role in the autoim mune process leading to childhood diabetes. The purpose of this study was t o evaluate the association between type 1 diabetes and the polymorphism enc oded by the HLA-DQB1 gene by using case-parents trios. The study area was t he metropolitan region of Santiago, Chile, and cases were ascertained from March 1997 to August 1998. Genotyping was performed in 94 trios comprising incident cases less than 17 years of age at the time of diagnosis and their parents. The transmission/disequilibrium test was used to detect different ial transmission in the HLA-DQB1 locus. The authors found that alleles DQB1 *0302 and DQB1*0201 were strongly associated with the disease. By using 1:3 matched sets of cases-pseudosibs and conditional logistic regression model s, allelic relative risks were estimated for DQB1*0302 (r = 7.2, 95% confid ence interval: 2.8, 18.5) and DQB1*0201 (r = 4.7, 95% confidence interval: 1.9, 11.6); DQB1*0301 was considered the baseline allele. When case-parents trios were used, alleles DQB1*0302 and DQB1*0201 were strongly associated with a higher risk of type 1 diabetes in the population of Santiago.