engleski

Two new microsatellite markers for insulin dependent diabetes mellitus

Insulin dependent diabetes mellitus (IDDM) is an autoimmune disease characterised by the T cell mediated destruction of the b cells in pancreas. The strongest association with the disease was found for HLA class II loci, but recent studies suggest the existence of additional non-HLA genes involved in the development of IDDM. In this study we analysed samples from 100 patients diagnosed with IDDM and 150 healthy unrelated individuals. Patients and controls were selected on the basis of their HLA class II alleles, and classified in 4 groups (DR3/DR4, DR3, DR4, non DR3/DR4). PCR-SSP method was performed for HLA class II typing. Three microsatellite loci located in the HLA region (D6S265, D6S273, and MIB) were amplified with PCR and subsequently analysed by electrophoresis on a 6% polyacrylamide gel in an ALFexpress sequencer. Comparison of patients and controls with respect to the allele distribution revealed differences for D6S273 and MIB loci while there was no difference observed for D6S265 locus. Alleles D6S273-126bp (p=0, 02565), D6S273-138bp (p=0, 01967), D6S273-140bp (p=0, 00035), MIB-348bp (p=0, 01302), MIB-350bp (p=0, 00677) and MIB-352bp (p=0, 02289) were present with an increased frequency among patients, while alleles D6S273-130bp (p=0, 02945) and MIB-334bp (p=0, 00105) appeared with decreased frequency. We also examined the possibility that these alleles showed association with disease as a result of their linkage with HLA class II genes, by excluding individuals positive for DR3 and/or DR4 antigens from further analysis. Difference was then observed only for alleles D6S273-132bp (p=0, 03986), MIB-332bp (p=0, 04376) and MIB-350bp (p=0, 01212). Comparison of DR3 and DR4 positive groups showed that other alleles were in linkage disequilibrium with HLA class II genes. In conclusion, our results suggest that D6S273 and MIB loci have an independent role in development of disease. For that reason these loci can be considered as two new possible susceptibility markers for IDDM in the Croatian population.

IDDM; microsatellites; HLA

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