LAUSR

Aim To analyze the human leukocyte antigen complex class I (-A, -C, and -B) and class II (-DRB1, and -DQB1) linked haplotypes of Chinese Han population, and to study the recombination events of the five classical loci in the inheritance of HLA haplotypes. Methods A total of 1409 peripheral blood samples were collected from 297 families in Chinese Han population who came to Shenzhen Blood Center for HLA typing. HLA-A/B/C/DRB1/ DQB1 alleles were typed with LABType® SSO HLA Typing Kits (One Lambda, Inc., Los Angeles, CA), then the recombination sites were analyzed by family study. The samples of 78 individuals from the families with exchange recombination were selected and sequenced with Next-generation sequencing (NGS) HLA typing method, to judge whether the recombination was interallelic exchange or interlocus exchaneg. The whole gene of HLA-A, -B, -C, and exons2,3 of HLA-DRB1 and DQB1,were PCR-amplified in a single PCR for each locus. Amplicons of each sample were pooled and processed using NGSgo® DNA library preparation workflow for Illumina MiSeq. Finally paired-end sequencing was performed on the Illumina MiSeq platform using a standard flow cell and data was analysed using HLA typing software NGSengine®. Results Among 815 offspring individuals of 297 families in Chinese Han population, 14 individuals with HLA-A-C-B-DRB1-DQB1 linked haplotypes had a recombination rate of 1.718%. Among 14 HLA haplotypes recombined family, 5 of them are found to have a crossover between HLA- A and -C loci and 9 of them have a crossover between HLA- B and -DRB1 loci. 6 of these recombination events occurred in the most common haplotypes A∗3303-Cw∗0302-B∗5801-DRB1∗0301-DQB1∗0201 of Chinese Han population.Among 14 cases of recombination, 8 of them were formed by a crossover between maternal chromosomes, 6 cases a crossover between paternal chromosomes. 5 individuals with an exchange between A/C loci are all females. Among 9 cases with an exchange between B/DRB1 loci, 8 of them were males and 1 case was female. Conclusions This research enlarged the HLA haplotypes genetic map of Chinese Han population, proving the valuable genetics data to the further research of the mechanism of HLA recombination. Meantime, NGS presents a significant technical advantage for resolving common ambiguities observed using current SBT method.