HLA related genetic risk for coeliac disease

Background: Several studies have shown an elevated prevalence of coeliac disease (CD) in sibs of coeliac patients (risk 8-12%). Aim and method: We evaluated the risk that sibs of children with CD will also develop CD. This cohort of 188 Italian families was composed of probands with CD, at least one sib and both parents. CD status was determined and human leucocyte antigen (HLA)-DQ genotyping performed in all family members. The study also used a dataset of Italian triads (127 probands and both their parents) also genotyped for HLA-DQ. Results: The overall risk that a sib of a CD patient will develop the disease was estimated at 10% in this sample. The risk estimate ranged from 0.1% to 29% when HLA-DQ information of the proband, parents and sib was considered. We found a negligible risk (lower than 1%) for 40% of the sibs of probands, a risk greater than 1% but less than 10% for 30%, and finally a high or very high risk (above 25%) in one-third of families. Conclusion: These results make it possible to provide more accurate information to parents with a child with CD about the real risk for another child. An antenatal estimate of the order of risk of CD is now possible. Specific follow-up can thus be offered for babies at high risk.