Is HLA-DQ typing useful in screening for celiac disease among Arabs with type 1 diabetes? A case-control study.

Objectives: The data on the usefulness of DQ-typing in screening for celiac disease (CD) among type 1 diabetic (T1D) patients came from the West. We conducted this study among T1D patients to: (1) determine the frequency of DQ-genotypes, (2) assess the risk associated with human leukocyte antigen (HLA)-DQ genotypes, and (3) identify the cost-effective screening strategy.

Methods: HLA-DQ genotyping was performed on 67 T1D patients with CD (cases) (mean age 15 years) and 224 T1D patients without CD (controls) (mean age 18.29 years) (2021-2023). The entry criterion for the control group was duration of T1D ≥5 years and negative annual celiac serology assay.

Results: On comparison of the cases versus controls, T1D patients carrying homozygous DQ2.5 genotype (30% vs. 13.8%) or DR3-DQ2.5 haplotype (81.3% vs. 65.7%) showed significantly "higher risk" (odds ratio [OR] = 2.64, p = 0.002; OR = 2.3, p = 0.008, respectively) to develop CD. Only 4% do not harbor any of the CD-at risk genotypes (DQ2.5, DQ8, or DQ2.2) and none developed CD. Heterozygous DQ8 was associated with a significantly lower risk of developing CD with OR of 0.123 (1.5% in cases vs. 10.3% in controls, p = 0.022).

Conclusion: Only 4% of Saudi patients with T1D carry DQ-genotypes at no risk to develop CD, which supports the European guidelines that recommend celiac serology test as the most cost-effective screening method. We identified the risk gradient associated with DQ-genotypes to develop CD in our population which could help in counseling patients for the risk to develop CD and planning follow-up serology tests.