XRCC4 and nasopharyngeal carcinoma: First, for the XRCC4 rs3734091 SNP, the controls had a frequency of 93.5% for the GG genotype, 6.3% for the GT genotype, and 0.2% for the TT genotype, whereas the NPC patients had a frequency of 87.5% for the GG, 11.1% for the GT, and 1.4% for the TT genotypes, respectively (Table 3).