Publication bias was assessed by Begg's test and Egger's test (data not shown) in the total population and all the subgroups. For the genotypic risk model, 5/5 vs. other genotypes, in which the HIV-1 exposed but seronegative samples (HESN) subjects were used as controls, both the Begg's test (p = 0.462) and the Egger's test (p = 0.215) did not present any significantly statistical evidence of publication bias. For the allelic risk model of 5-repeat allele vs. other alleles, in which the HIV-1 exposed but seronegative 