Prevalence of haplotype DQ2/DQ8 and celiac disease in children with type 1 diabetes

Type 1 diabetes (T1D) and celiac disease (CD) coexist very often. Identification of the human leukocyte antigen (HLA) DQ2/DQ8 can confirm the genetic predisposition to CD. Negative result of this test allows to exclude CD with a high probability. It was suggested that in individuals with higher risk of CD, including T1D patients, the implementation of genetic testing should reduce the number of patients requiring systematic immunological screening. The aim of this study was to analyze the prevalence of different haplotypes predisposing to CD in children and adolescents with previously diagnosed T1D. Material and methods: A retrospective analysis was performed on 166 T1D children (91 girls) in whom HLA DQ2/DQ8 alleles were tested. In 9.6% CD was also diagnosed. Results: In 12.7% both HLA DQ2/DQ8 were negative. In 87.3% patients HLA DQ2 and/or DQ8 was positive, including 27.7% patients with both haplotypes DQ2.5 and DQ8 positive. In all CD patients the disease predisposing alleles were positive, while none of the HLA DQ2/DQ8 negative children were diagnosed with CD. Conclusions: The prevalence of HLA DQ2.5 and the HLA DQ2.5 / HLA DQ8 configuration is higher in patients with T1D, and CD compared to children with T1D alone. The combination of HLA DQ2 and HLA DQ8 most significantly increases the risk of developing CD. The group of HLA DQ2/DQ8 negative patients with improbable CD diagnosis, is relatively small. Most of T1D patients HLA DQ2/DQ8 positive need further regular antibody assessment. In patients with T1D, who are at high risk of developing CD, genetic testing may be considered to select those who require further systematic serological evaluation. Due to its retrospective nature, the study was not registered in the database of clinical trials and the Clinical trial registration number is not available.