Frequency of HLA-DQA1*0501 and DQB1*0201 alleles in patients with coeliac disease, their first-degree relatives and controls in Jordan.

Background: The primary genetic marker associated with coeliac disease (CD) is the HLA-DQ2 molecule, encoded by the DQA1*0501 and DQB1*0201 genes.

Aim: To investigate the frequency of HLA-DQA1*0501 and DQB1*0201 alleles in Jordanian patients with CD and their first-degree relatives.

Methods: An allele-specific DNA-based PCR-sequence-specific primer was used to investigate DQA1*0501 and DQB1*0201 alleles in 44 CD patients, 47 first-degree relatives and 53 healthy controls.

Results: The mean age of the patients at the time of diagnosis was 13.5 years (range 1-39) and at the time of the study was 19.3 years (range 5-42). The DQA1/B1 (0501; 0201) haplotype was present in 80% of patients and 66% of first-degree relatives compared with 32% of controls (p<0.0001 and <0.01, respectively). The remaining 20% of CD patients who were negative for the DQ2 molecule carried the DQB1*0201 allele only. A statistically significant difference was detected in the DQ2 hetero-dimer frequency between CD patients, their first-degree relatives and controls with a higher frequency in the patients group (p<0.001).

Conclusion: The significant differences in the frequency of DQA1*0501, DQB1*0201 alleles in CD patients and their first-degree relatives compared with the control group demonstrated the important role of these alleles in the development of CD in the Jordanian population.