Background: Genes of HLA complex on chromosome 6p21 principally contribute to the genetic risk of insulin-dependent diabetes mellitus type I (T1 DM). Associations of HLA class II loci allelic variants with T1 DM are well established. Another prime candidate, particularly the polymorphic DPB1 gene, has been reported as probably contributing to the disorder, but its relative contribution to the predisposition to the disease is difficult to assess due to strong linkage disequilibrium of HLA alleles. DPB1*0301 and DPB1*0202 have been reported as positively and DPB1*0402 as negatively associated alleles in different Caucasoid populations (predisposing versus protective alleles, respectively).
Objectives: The aim of this study was to establish the occurrence rates of HLA-DPB1 alleles in patients suffering from T1 DM and to compare them with those in healthy subjects.
Methods: A PCR-SSP method was performed to identify HLA-DPB1 alleles in 61 patients and 160 healthy controls. The exact Fisher's test was used to determine the statistical significance of allele frequency differences between patients and control subjects.
Results: The analysis of obtained results has shown a significantly decreased frequency of DPB1*0402 and slightly increased occurrence rates of DPB1*0101 and DPB1*1301, respectively in the investigated group of patients. Neither DPB1*0301 nor DPB1*0202 were observed to be over-represented.
Conclusions: The expected significant decrease in the frequency of DPB1*0402 was confirmed, whereas positive associations with DPB1*0301 and DPB1*0202, did not prove to be true, respectively (Tab. 1, Ref: 19).