DQA1 and DQB1 HLA genes as markers of insulin-dependent diabetes mellitus in the Polish population

The second-generation screen of human genome has confirmed that HLA region genes play a key role in the susceptibility to insulin-dependent diabetes mellitus. The aim of the present study was to estimate the frequency of chosen alleles of DQA1 and DQB1 genes in the patients with insulin-dependent diabetes mellitus and their first degree relatives in comparison to the healthy population in the north-eastern region of Poland. HLA typing of DQA1 and DQB1 alleles of the HLA region was performed by "phototyping" PCR-SSP method. The highest predisposition to IDDM in the population of the north-eastern region of Poland was associated with DQB1*0302 allele and DQB1*02-DQA1*0301 or DQB1*0302-DQA1*0301 haplotypes, while the dominant protection was connected with DQB1*0602, DQB1*0603 and DQB1*0301 alleles. The high frequency of protective DQB1*0602 and DQB1*0603 alleles and the low percentage of "diabetogenic" DQB1*0302 genes in the healthy control population of north-estern region of Poland may suggest their dominant influence on the relatively low incidence of IDDM in this region. The relatively high percentage of the first degree relatives of IDDM patients with pancreatic autoantibodies but with protective alleles observed in our study, which significantly decreases the risk of IDDM, suggests the necessity of DQB1*0602-03 measurements in such subjects for the better IDDM risk assessment.