Objective: To assess the prevalence of coeliac disease (CD) among first grade relatives of children with CD and relationship of familial incidence of CD with different HLA-DR, DQ haplotypes of children with CD. Patients and methods: In 128 first grade relatives of 30 children with CD diagnosed according to ESPGHAN criteria of 1990 (and typified HLA class II loci DR/DQ) total IgA were examined as well as antiendomysial antibodies in class IgA (EMA) and antibodies against tissue transglutaminase in class IgA (tTG). The group comprises young parents and a small number of siblings. EMA were assessed by the indirect immunoperoxidase reaction (Binding Site, UK), tTG were assessed by the ELISA method (Orgentec, Diagnostika GmbH, Germany), HLA typing was implemented by the PCR-SSP method. Results: In none of the relatives serum IgA deficiency was proved. Eight relatives (3 fathers, 3 brothers, 1 mother, 1 sister) had positive EMA and tTG. All were subjected to enterobiopsy (EB). In 7 instances atrophic jejunal mucosa was found, in one instance normal jejunal mucosa with a large number of intraepithelial lymphocytes, thus in 6 instances a silent and in one instance a potential form of the disease is involved. Prevalence of CD among grade 1 relatives is 6.25%, prevalence among parents 4.3% and among siblings 11.4%. The risk of the disease among siblings
= 34.5. Prevalence in related homozygotes DR3/DQ2 is 10.5% (RR = 31.8), in heterozygotes DR3/DQ2 6.25% (RR = 18.9), in heterozygotes DR5,7/DQ2 2.7% (RR = 8.39). Conclusions: Prevalence of CD among grade 1 relatives is 6.25%, it is higher in siblings than in parents. The highest prevalence of CD in grade 1 relatives is in patients who are homozygotes for DR3/DQ2.

        Key words: coeliac disease, familial incidence of endomysial antibodies, antibodies against tissue transglutaminase, HLA haplotypes