[Exclusion of HLA-C Genotype with Zero Mismatched PCR-SBT Results by Next Generation Sequencing]

Three cases of rare alleles of HLA-C with zero mismatched PCR-SBT results were analyzed by full-length sequencing to determine the true genotypes.

Three rare HLA-C alleles with zero mismatched PCR-SBT results were screened from clinical transplant matching samples, and the full-length sequence was detected by next-generation sequencing technology.

The results of PCR-SBT typing of 3 samples were: HLA-C*03:04, 12:167; HLA-C*07:291, 15:02; HLA-C*01:43, 08:16. Other alleles were not in the CWD table of common and confirmed HLA alleles in China (version 2.3) except common allele HLA-C*03:04, HLA-C*15:02. NGS full-length sequencing revealed that the HLA-C genotypes of the three samples were a combination of common alleles and novel alleles, and the three novel alleles had a base mutation in exons 6, 2, and 4, respectively. The novel allele sequences have been submitted to the Genbank database (MK629722, MK335474, MK641803), which were officially named HLA-C*03:04:74, HLA-C*15:192, HLA-C*08:01:25 by the WHO HLA Nomenclature Committee. The HLA high-resolution typing results of 3 samples were: HLA-C*03:04:74, HLA-C*12:03; HLA-C*07:02, HLA-C*15:192; HLA-C*01:02, HLA-C*08:01:25.

HLA typing results containing rare alleles should be treated cautiously, and the full-length sequence should be verified by NGS or cloning. The laboratory finally confirmed that the 3 cases of PCR-SBT zero mismatch HLA-C genotypes are the combination of common alleles and novel alleles by NGS sequencing, which provides an accurate basis for clinical transplantation matching and enriches the human HLA genetic database.