RESUMO
Restriction fragment length polymorphism (RFLP) analyses of DR1 positive peripheral blood leukocytes DNA was carried out. The Taq I digested DNA was hybridized with cDNA probes for HLA-DR and -DQ beta genes. The DR probe detected fragments commonly observed in the DR1 specificity, whereas a new DQ-beta fragment was detected in some DR1 haplotypes when the DQ-beta probe was used. This fragment had an RFLP pattern identical to the DQ-beta fragment typically associated with most DR2 and some DRw6 specificities.
Assuntos
DNA/análise , Genes MHC da Classe II/genética , Antígenos HLA-DQ/genética , Antígenos HLA-DR/genética , Antígenos de Histocompatibilidade Classe II/genética , Polimorfismo de Fragmento de Restrição , Alelos , Sondas de DNA , Feminino , Cadeias beta de HLA-DQ , Cadeias HLA-DRB1 , Humanos , MasculinoRESUMO
Class II antigen genes encoded by the major histocompatibility complex region (HLA-D region) in man play an important role in susceptibility to insulin dependent diabetes mellitus (IDDM). Evidence suggests that the DQ subregion within the HLA-D region is more directly responsible for susceptibility to IDDM. Therefore, we designed a synthetic oligonucleotide specific for the DQ beta gene to further the understanding of the disease association with HLA-D region genes at the molecular level. Restriction fragment length polymorphism (RFLP) analysis was carried out using DNA isolated from nine families, each including at least two affected siblings (a total of 37 siblings). The segregation pattern of hybridizing fragments showed that: (1) for each of the DR2, DR3, and DR4 specificities, two different alleles can be identified by the DQ beta probe; (2) a 1.9 kb-Taq 1 fragment with the DR4 specificity and a 6.0 kb-Taq-1 fragment within the DR2 specificity tend to cosegregate with IDDM; (3) there was no preferential segregation of the two alleles detected within the DR3 specificity (one allele identified by a 4.7 kb-Taq 1 fragment is quite common among individuals with the DR3 specificity). The results from this study add to the evidence that certain DQ alleles appear to be more directly associated with the diabetogenic gene (or genes) in certain DR specificities.
