NKG2C copy number variations in five distinct populations in mainland China and susceptibility to nasopharyngeal carcinoma (NPC)

In this study, copy number variation (CNV) of NKG2C gene was investigated in 1129 normal, unrelated individuals representing two southern Chinese Han populations (Hunan Han and Guangdong Han), two northern Chinese populations (Inner Mongolia Han and Inner Mongolia Mongol) and one southeastern Chinese Han population (Fujian Han) using polymerase chain reaction-sequence-specific priming (PCR-SSP) method. CNV of NKG2C gene did not vary significantly among the five Chinese populations, with NKG2C gene deletion showing a frequency ranging from 0.2031 to 0.2688. Compared with worldwide ethnic groups, very significant difference was observed between the five Chinese populations and the Mexican mestizos (all P_corrected=0.0025), and between the Fujian Han population and the German population (P_corrected=0.005). We further examined CNV of NKG2C and HLA-E allelic distribution in 653 patients afflicted with nasopharyngeal carcinoma (NPC) in Hunan province. Neither CNV of NKG2C nor HLA-E was associated with NPC. There was a trend of reduced NPC risk in individuals who were homozygous for both HLA-E^*01:03 and NKG2C deletion (0.46% vs. 2.51%, P=0.0076, P_corrected=0.0684, OR (95% CI)=0.1794 (0.0473-0.6809)). Taken together, our results suggest that NKG2C deletion and HLA-E signalling pathway does not play a major role in determining genetic susceptibility to NPC.