OR27 Detection of thousands of novel KIR alleles with high-throughput NGS typing via neXtype

Abstract

Aim The killer cell immunoglobulin-like receptor (KIR) gene family is seen to play an important role in unrelated hematopoietic stem cell transplantations. Allele level KIR genotyping may improve the donor selection process. The IPD-KIR database currently comprises 753 alleles. With our newly established high-throughput workflow for KIR allele-level typing, we discovered a vast number of previously unknown variations of KIR alleles. Methods We perform cost efficient KIR allele level genotyping based on a paired-end short-amplicon approach by NGS using Illumina HiSeq 2500 instruments. The amplicons cover exons 3, 4, 5, 7, 8 and 9 of each KIR gene. Our neXtype software was adapted to report KIR genotyping results at allelic Level. Results Starting in October 2016, we added KIR allele-level typing to the DKMS standard genotyping profile for new potential donors and already applied it to more than 500,000 samples. Since then, we have detected more than 5000 distinct novel SNP sequences, see Fig. 1, i.e. sequences that differ from the reported alleles by at least one nucleotide. About half of the novel sequences exhibit new protein sequences. In addition, we identified many alleles with so far unreported combinations of described exon sequences. We analyzed the distribution of new variants according to ethnic self-assessment of recruited donors. Conclusions The ability to genotype KIR genes at allelic level in a high-throughput framework gives the opportunity to detect a huge number of unknown sequences on a rather short time scale. Consequently, the database of currently named alleles can be extended significantly and thus gives input to studies around the complex KIR gene Family.