We also performed stratified analyses by ethnicity and sample size to explore potential sources of heterogeneity and examine the relationship between the DC-SIGNR VNTR polymorphism and susceptibility to HIV-1 infection. The results are also summarized in Table S2 . Most of the results of the stratified analyses were consistent with the main analysis. For ethnicity, the studies were divided into two subgroups, one subgroup of Asian descendants (7 studies) and the other subgroup of European-American descendants (2 studies). The resistance to HIV-1 infection found among 5/5 homozygous subjects was predominantly due to the HIV-1 exposed seronegative (HESN) subjects of the Asian population (OR = 0.58, 95% CI = 0.39-0.85, p = 0.006, Pheterogeneity = 0.34 and I 2 = 12%) ( Figure 4A ). The 5-repeat allele presented the trend of having the protective effect among Asian (OR = 0.84, 95% CI = 0.71-1.00, p = 0.05, Pheterogeneity = 0.20 and I 2 = 33%), though the p value was marginal ( Figure 4B ). This result also showed that the sample size of the Asian population in present study was not large enough to achieve enough statistical power to obtain significant observations. As there was only one study performed with African and European-Americans involving HIV-1 patients and HIV-1 exposed seronegative (HESN) controls, the stratified analyses in these populations were not performed.