High prevalence of coeliac disease in siblings of children with type 1 diabetes

Coeliac disease has been shown to occur more frequently among first-degree relatives of diabetic patients than in the general population. Our objective was to assess the prevalence of endomysium antibodies (EMA) in non-diabetic siblings of Czech diabetic children and to evaluate the effects of HLA-DQ polymorphisms in determining the genetic susceptibility to coeliac disease (CD) in these subjects. We investigated 240 siblings of diabetic children from 213 families (125 males and 115 females, aged 12.6±4.9 years, mean ± SD). All subjects were tested for the total IgA level to exclude IgA deficiency, and for endomysium IgA to disclose CD. In five IgA-deficient subjects, anti-gliadin IgG was used instead. Small bowel biopsy was offered to subjects with confirmed positive EMA. The HLA-DQA1, -DQB1 genotypes were determined using PCR-SSP. Positive EMA were found in 9/240 (3.8%) subjects (three males, six females). The biopsy confirmed CD in six children, two had a normal mucosal finding and one refused the biopsy. The HLA-DQ2 polymorphism was more frequent among siblings with EMA (seven of nine) than in siblings without EMA (33%), corrected P =0.031. Conclusion:The 3.8% frequency of coeliac disease found in siblings of diabetic children is close to the 4.3% found previously in Czech children with type 1 diabetes mellitus and is substantially higher than the rate in the healthy children population.