MOLECULAR CHARACTERIZATION OF HLA CLASS-II GENES IN CELIAC-DISEASE PATIENTS OF LATIN-AMERICAN CAUCASIAN ORIGIN

In the present study, the polymorphic domain of HLA class II genes pre sent in a pediatric population of Argentinian celiac disease patients was analyzed by hybridization to sequence-specific oligonucleotides an d DNA sequencing. Sixteen out of 16 DR5/7 heterozygous patients bore t he DQA10501 and DQB1*0201 alleles implicated in the DQ2 risk specific ity. The second exon of DQA1, DQB1 and DRB1 genes from 2 DR5/7 patient s was characterized by DNA sequencing. The following alleles were foun d in both patients: DRB11101 and DRB1*0701; DQB1*0301 and DQB1*0201; DQA10501 and DQA1*0201. Previous serological analysis in this populat ion had shown the presence of DQ2 in 95% of the patients (40% in contr ols) and a negative association with DQ1 haplotypes, suggesting the pr esence of other ''permissive'' or neutral alleles. The following HLA-D QB1 alleles, besides DQB10201, were identified in 31 CD patients: DQB 10301, 0302, 0401 and 0402. All these alleles share a common pattern of residues between positions 84 and 90, and distinct from that presen t in DQ1-related alleles.