Polymorphism of short tandem repeat of exon 5 of MHC class-I chain related gene A and association with nasopharyngeal carcinoma in a southern Chinese population

Objective: To explore the association between the short tandem repeat polymorphism of exon 5 of MICA gene(MICA-STR) and nasopharyngeal carcinoma (NPC) in a southern Chinese population. Methods: One hundred and twenty-seven consecutive NPC patients and 112 randomly selected normal controls residing in southern China mainland were analyzed for MICA-STR allelic variation and MICA gene deletion by fluorescent polymerase chain reaction-genescanning and polymerase chain reaction-sequence specific priming. Results: MICA * A9 was observed at significantly higher frequency in the NPC patient group than in the control group (relative risk = 2. 524, P = 0. 001, P_c = 0.006); whereas MICA * A5.1 was present at significantly lower frequency in the NPC patient group than in the control group (RR = 0.418, P - 0.0004, P _c = 0.0026). Further analysis revealed that MICA * A9 was over-represented in male NPC patients, compared with male controls (RR = 3.23, P = 0.00095, P_c = 0.006) ; whereas MICA * A5.1 was present at significantly lower frequency in male NPC patients, compared with male controls(RR = 0. 372, P = 0.0007, P_c = 0.004). None of the MICA-STR variants showed statistically significant frequency difference between female NPC patients and female controls (P_c > 0.05). Conclusion: MICA-STR polymorphism is associated with NPC, and MICA * A9 is a genetic susceptibility marker of male individuals for NPC in a southern Chinese population.