High-resolution genotyping of HLA-DQA1 in the GoKinD study and identification of novel alleles HLA-DQA1*040102, HLA-DQA1*0402 and HLA-DQA1*0404.

In order to achieve high-resolution HLA-DQA1 genotyping, it is necessary to identify polymorphisms in exons 1, 2 and 3. We present a high-resolution sequence-based typing (SBT) strategy for genotyping exons 1, 2 and 3 of the polymorphic HLA-DQA1 locus. This method is an improvement upon previously presented methods, because it utilizes the minimum number of SSP-PCR assays to obtain clear DNA sequence in both the forward and reverse directions of all three exons. All known HLA-DQA1 alleles are resolved with the exception of HLA-DQA1*010101 and HLA-DQA1*010102 for which the distinguishing polymorphism is located in exon 4 and does not result in an amino acid change. This method has enabled our laboratory to identify three new HLA-DQA1 alleles - HLA-DQA1*040102, HLA- DQA1*0402 and HLA-DQA1*0404 - in the Genetics of Kidneys in Diabetes (GoKinD) study population. Additionally, we present single-allele amplification methods, which identify the coding sequences of HLA-DQA1 exons 1, 2, 3, intron 2 and 300 bp of the HLA-DQA1 promoter (QAP). This study, also describes the QAP for most of the known HLA-DQA1 alleles, three HLA-DQA2 promoter sequences and the intron 2 sequences for HLA-DQA1*040101, HLA-DQA1*040102, HLA-DQA1*0402 and HLA-DQA1*0404.