Allelic diversity of KIR2DL4 gene and identification of five novel alleles among southern Han Chinese population

Objective To study the polymorphisms of the KIR2DL4 gene in a southern Han Chinese population. Methods Genomic DNA isolated from 306 unrelated individuals was amplified by using KIR2DL4-specific PCR primers. The PCR products were genotyped for the entire coding sequence by sequencing-based typing (SBT). Assignment of allelic profile was accomplished with an Assign 3.5 software. For samples with inconclusive SBT results, the RT-PCR products covering the entire coding sequence of the KIR2DL4 gene were subjected to cloning and haplotype sequencing. Results Among the 306 individuals, 11 alleles were detected, of which 5 novel alleles were officially named by the KIR subcommittee of the World Health Organization Nomenclature Committee for factors of HLA system. The observed frequencies for the 11 alleles were KIR2DL4*00102 (75.5%), *00103 (8.2%), *00501 (34.0%), *00503 (0.7%), *00504 (0.7%), *00602 (14.4%), *00801 (11.4%), *011 (22.2%), *032 (0.3%), *033 (0.3%) and*034 (0.3%). The ratio of 10A type alleles including 2DL4*00102, *00103, *00501, *00503, *00504, *00602, *032, *033, *034 and 9A type alleles including 2DL4*00801, *011 were 97.0% and 33.0%, respectively, with a ratio of 2.9 : 1. Conclusion The allelic diversity of the KIR2DL4 gene in southern Han Chinese has been elucidated, which may provide valuable data for research on transplantation, reproductive immunity, KIR-associated disease and evolution. Key words: KIR2DL4 framework gene; Sequence-based typing; Novel allele; Complementary DNA; Cloning and haplotype sequencing