Frequency of celiac disease and distribution of HLA-DQ2/DQ8 haplotypes among siblings of children with celiac disease.

Background: Celiac disease (CD) is a multifactorial disease, but genetic factors play a major role in its etiology. It has been known that human leucocyte antigen (HLA)-DQ2/DQ8 haplotypes are one of the most important predisposing genetic factors. The risk of developing CD in first-degree relatives and especially siblings of celiac patients is quite high because of having the same HLA haplotypes.

Aim: To evaluate the frequency of CD and the distribution of the HLA-DQ2/DQ8 haplotypes in siblings of celiac patients.

Methods: Patients with biopsy-proven CD and their siblings were included in the study; those who did not have HLA genotyping were excluded from the study. All siblings were on a gluten-containing diet. The HLA genotyping, tissue transglutaminase antibody IgA antibody test, and total IgA test were performed in all participants.

Results: A total of 57 celiac patients and their 112 siblings were included in the study. The mean age of celiac patients and siblings were 10.30 ± 3.87 years and 9.90 ± 6.11 years, respectively. HLA-DQ2/DQ8 alleles were detected in 98.2% of patients with CD and 90.2% of siblings of celiac patients. HLA-DQ genotypes were present in all siblings diagnosed with CD. Tissue transglutaminase antibody IgA test was found to be positive in 16 siblings. CD was diagnosed in 12 siblings (10.7%) by intestinal biopsy.

Conclusion: The prevalence of CD was found to be 10.7% in siblings of celiac patients in our study. One-third of the siblings diagnosed with CD were asymptomatic. We detected HLA-DQ alleles in 98.2% of celiac patients and 100% in siblings diagnosed with CD. In addition, 1 of the 2 siblings was diagnosed with CD 1 year later and the other 4 years later. Therefore, we suggest that siblings of celiac patients should be followed up with clinical findings as well as HLA analysis and serological examination. Since the risk of developing CD is much higher in asymptomatic siblings, we recommend that siblings should be screened for CD even if they are asymptomatic.