In the primary analysis for allelic risk model of the 5-repeat allele vs. the other alleles, using the healthy individuals as controls, the value of X 2 was 9.52 with 7 degrees of freedom, and p was 0.22 in a fixed effect model (Figure 2A ). The I 2 was 27%, suggesting a low to moderate heterogeneity. The fixed effect model was applied to synthesize the data. Overall, the OR was 1.03 (95% CI = 0.93-1.15) and was not significant (Figure 2A ). On the other hand, using the HIV-1 exposed but seronegative (HESN) samples as controls, the value of X 2 was 8.84 with 6 degrees of freedom, and p was 0.18 ( Figure 2B ). The I 2 was 32%, suggesting a moderate heterogeneity.