Leukocyte immunoglobulin-like receptor A3 gene deletion in five Chinese populations and protective association with nasopharyngeal carcinoma.

Among the thirteen leukocyte Ig-like receptor (LILR) loci located at 19q13.4, LILRA3 is unique in that it encodes a soluble protein lacking the transmembrane and cytoplasmic domains, and a 6.7 kb deletion spanning the first seven exons has been detected in some human individuals. Presently, there is a lack of data about the distribution of LILRA3 gene deletion in more diverse ethnic groups. Also, no previous studies have investigated the correlation between copy number variation (CNV) of LILRA3 and nasopharyngeal carcinoma (NPC). In this study, five populations from China mainland: two Southern Han populations, Hunan (N = 1478) and Guandong (N = 107); one Southeastern Han population, Fujian (N = 439); and two Northern populations, Inner Mongolia Han (N = 104) and Mongol population from Inner Mongolia (N = 158) were investigated for CNV of LILRA3 using polymerase chain reaction-sequence-specific priming (PCR-SSP) method. LILRA3 variants were also examined in a cohort of NPC cases (N = 1142) in Hunan Han population. The five Chinese populations demonstrated northward increase in frequency of the deleted form of LILRA3 gene (LILRA3Del) (all corrected p values < 0.05). Inter-population comparison also uncovered significant differentiation in the distribution of CNV of LILRA3 among modern human populations. LILRA3Del was found to confer significantly reduced risk to NPC in Hunan Han population (at allelic level: OR = 0.79, 95% CI = 0.71-0.89, p < 0.0001; at genotype level: OR = 0.63, 95% CI = 0.51-0.79, p < 0.0001). No interaction was found between LILRA3 variants and HLA-A02:07, HLA-A11:01, HLA-B13 and HLA-B46:01 alleles in susceptibility to NPC. Our study constitutes the first demonstration of LILRA3 gene as a locus linked to NPC susceptibility in a southern Chinese population. Future independent studies in other populations are warranted to confirm the findings reported in this study.