HLA associated type 1 diabetes risk in children of Pakistani migrants to Norway

Abstract

Type 1 diabetes (T1D) results from poorly defined interaction between susceptibility genes and environmental factors. The objective was to investigate Human Leukocyte Antigens (HLA) associated T1D risk among Pakistani newborns in Norway based on what published globally. DNA samples from 189 newborns, whose parents were first generation migrants from Pakistan, were analyzed. The hypothesis was tested using high resolution HLA genotyping for the -DRB1 and -DQB1 loci and high/intermediate for the -DQA1 locus. We identified 28 different DRB1, 13 DQB1 and 9 DQA1 alleles. Of the 39 different haplotypes identified, only five have been reported to confer T1D susceptibility. Among these the DR3-DQ2 (DRB1*03:01:01-DQA1*05-DQB1*02:01:01) haplotype was found in 18.5% (n=70) of the newborns, and 18.6% (n=13) of these were homozygotes. A diverse range of HLA haplotypes were identified amongst an ethnically homogenous group of newborns, with only a small proportion associated with T1D risk. The incidence of T1D among immigrants form South/East Asia is the lowest in the Norwegian Type 1 Diabetes Registry. The few included so far, are children of first generation immigrants. If incidence of T1D rises in the Norwegian Pakistani childhood population, as observed in the UK, then environmental triggers rather than genetic susceptibility will be the explanation.