The involvement of the HLA-DQB1 alleles in the risk and the severity of Iranian coeliac disease patients.

Coeliac disease (CD) is a highly prevalent autoimmune disorder that is triggered by the ingestion of wheat gluten and related proteins in genetically susceptible individuals. The CD is associated with human leucocyte antigen (HLA) genes particularly with HLA-DQ alleles encoding HLA-DQ2 and DQ8 proteins. To define risk and severity alleles for CD, a total of 120 definite CD patients and 100 healthy controls were genotyped for HLA-DQB1 gene. HLA-DQB1 genotyping was performed in all patients and controls using PCR-SSP technique, and to evaluate the clinical relevance of testing for HLA-DQB1 and determining absolute risk of disease, prevalence-corrected positive predictive value and prevalence-corrected negative predictive value (PcPPV and PcNPV) were calculated. Our results for a first time show that DQB1*02:00 and DQB1*03:02 alleles and DQB1*02:01/03:02 genotype very significantly associated with increased risk of patients with CD, and DQB1*03:01,4 allele provides protection against CD in Iranian patients. Furthermore, the PcPPV for DQB*02:01 and 03:02 alleles in CD were 0.014 and 0.012, respectively, and the highest absolute risk presented by DQB*0201/0302 genotype (PcPPV = 0.079) and 98% of patients with CD carried DQB1*02:01/x or DQB1*03:02/x genotype. The results also clearly demonstrated that the DQB1*02:01 allele significantly associated with severity of CD, while DQB1*03:02 allele associated with mild form of CD. These results suggest that clinically suspected individuals for CD and first-degree relatives of patients with CD to be screened for HLA-DQB*0201 and DQB*0302 alleles for possible early diagnosis and treatments.