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The presence of dental enamel defects in coeliac disease and their relation to hypocalcaemia or a particular HLA class in 82 Italian children with coeliac disease was studied. Demarcated opacities or hypoplasia were detected in 23 subjects (group 1) while minimal or no dental lesions were found in the remaining 59 patients (group 2); in 189 normal controls, enamel lesions were significantly less frequent than in patients with coeliac disease (14.8% versus 28.0%; p < 0.005). No statistically significant differences were found for age at diagnosis and calcium concentrations between groups 1 and 2. Regression analysis showed a correlation between age at diagnosis and number of teeth with enamel defects. In our patients, the presence of HLA DR3 antigen significantly increased the risk of dental lesions, while genotype DR5,7 seemed to protect against enamel defects. A logistic regression analysis of the variables age, serum calcium concentrations, number of affected teeth, type of enamel defect and DR antigens showed that only DR antigens discriminated coeliac disease patients with from those without enamel defects.

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In order to assess the effect of the HLA region on familiality of coeliac disease (CD), we carried out a study on 121 CD index cases and 325 first degree relatives. The transmission disequilibrium test confirmed the importance of the HLA-DR3 haplotype in CD susceptibility. However, the different distortion found in affected children inheriting maternal or paternal DR3 alleles suggested that the sex of the parent might influence the risk conferred by this haplotype. The increase in risk to siblings of affected individuals relative to the risk in the general population (λ s ) and the contribution of the HLA genes to this clustering (λ sHLA ) have also been estimated. Non-overlapping data from the literature have been collected and combined with our sample to extend such analysis. Then, the percentage contribution of the HLA region to the development of CD among siblings was 36n2%. This result confirms that the HLA genotypes are an important genetic background to CD development but shows that additional susceptibility factors remain to be identified.

HLA phenotypes of 64 Italian pediatric patients with celiac disease (CD) were compared with those of a group of healthy controls. DR3 and DR7 are significantly increased as reported in other populations. In addition an increase of heterozygotes DR5/DR7 was observed in our patients. The Hardy-Weinberg distribution in the patients group shows a disequilibrium due to the genotype DR5/DR7. Our data confirm that more than one HLA gene product is associated with CD: one with DR3 and the other with DR7.

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Single-strand conformation polymorphism (SSCP) has been developed as a method for detecting the presence of mutations in a segment of DNA. We applied it to the subtyping of the DRII group of alleles. The SSCP patterns of DRB I-DR52 group-specific products were defined in cell lines representing the DRBI*1101-06 alleles, using non-denaturing acrylamide gel electrophoresis and silver staining. Only one set of gel electrophoresis conditions was able to discriminate the DRII alleles tested. The protocol was validated in an analysis of 105 DRll-positive individuals previously typed by oligonucleotides probing. The study demonstrates the suitability of the SSCP technique to define the DRB 1*1101-06 alleles, the technique being particularly valuable in confirming and extending the oligotyping of DRBI-DR52 heterozygous samples.analysis and heteroduplex analysis (Sorrentino et al., 1992;D' Amato & Sorrentino, 1994;Savage et al., 1995). SSCP is based on the different mobilities of DNA single strands in non-denaturing electrophoresis conditions, depending on their sequences and, consequently, on the secondary structures they assume during the migration (Orita et al., 1989). This powerful technique allows the discrimination of a single mutation in a fragment of DNA under the right conditions, even if it is not able to define its