[HLA-DQ genotyping using a modified technique of PCR-RFLP: application to HLA-DQA1 gene]

Since 1989, several HLA-DQA1 PCR-RFLP genotyping protocols have been published. These methods require complete digestion of the PCR products and determination of the restriction fragments length. The HLA-DQA1 PCR-RFLP genotyping protocol describe here uses one amplification step through PCR, digestion of the PCR-products with 8 restriction endonucleases, and determination of the fragments size after polyacrylamide gel electrophoresis. Five of the enzymes, having no more than one restriction site in each allele (ApaLI, HphI, BsaJI, FokI and MboII), allow distribution of all the genotypes in 19 allelic-combination groups on the base of the digestion pattern: cut/not cut. Three additional enzymes (MnlI, DdeI and RsaI), having at least 2 restriction sites in each allele, are used to assign the genotype in each allelic-combination group on the base of the restriction fragments length observed. Eight of the 13 alleles, 36 of the 91 HLA-DQA1 genotypes could be characterized. Four to 8 samples could be characterized each day, including DNA extraction. The number of endonucleases used could act as internal control of enzymatic activities and the genotyping protocol can include new HLA-DQA1 alleles without modification of the experimental steps. This protocol can be applied easily in a laboratory without specific technical training or specific equipment.