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Objective. It has been reported that some single-nucleotide polymorphisms ( -13910C/T, -22018G/A, -13907C/G, -13915T/G, and -14010G/C) within the lactase gene are associated with lactase persistence. In our previous study, we found that -13910C/T is not a good predictor of lactase persistence in Chinese populations. To obtain a better understanding of the mechanism of lactase persistence, we examined the frequencies in Northern China of the four other alleles that are associated with lactase persistence. Material and methods. We evaluated the allele frequencies of -22018G/A, -13907C/G, -13915T/G, and -14010G/C in six northern Chinese populations (Manchu, Mongol, Hezhen, Oroqen, Kazak, and northern Han) using the methods of polymerase chain reaction–restriction fragment length polymorphism and resequencing. Results. By genotyping 1092 chromosomes, we found that the frequency of the -22018A allele was highest in the Kazak population and extremely low in the northern Han population. Although there are little available data about the frequency of lactase persistence in northern Chinese populations, we compared the allele frequencies with the phenotype frequencies that have been published previously. We found that the frequency of the -22018A allele was basically consistent with the reported frequencies of lactase persistence in Northern China. With respect to the -13907C/G, -13915T/G, and -14010G/C polymorphisms, we found no individuals with the derived allele. Conclusions. The frequency of the -22018A allele differed significantly among the six populations and the frequency reflected the frequency of lactase persistence. Taking into consideration the results of previous studies, we believe that the origins of lactase persistence-associated alleles are different in different pastoral populations. [ABSTRACT FROM AUTHOR]

Background and Aims. Men who have sex with men (MSM) are at high risk of HIV infection. The nonhomologous end joining (NHEJ) pathway is the main way of double-stranded DNA break (DSB) repair in the higher eukaryotes and can repair the DSB timely at any time in cell cycle. It is also indicated that the NHEJ pathway is associated with HIV-1 infection since the DSB in host genome DNA occurs in the process of HIV-1 integration. The aim of the present investigation was to evaluate associations of single-nucleotide polymorphisms (SNPs) in NHEJ pathway genes with susceptibility to HIV-1 infection and AIDS progression among MSM residing in northern China. Methods. A total of 481 HIV-1 seropositive men and 493 HIV-1 seronegative men were included in this case-control study. Genotyping of 22 SNPs in NHEJ pathway genes was performed using the SNPscan™ Kit. Results. Positive associations were observed between XRCC6 rs132770 and XRCC4 rs1056503 genotypes and the susceptibility to HIV-1 infection. In gene-gene interaction analysis, significant SNP-SNP interactions of XRCC6 and XRCC4 genetic variations were found to play a potential role in the risk of HIV-1 infection. In stratified analysis, XRCC5 rs16855458 was significantly associated with CD4+ T cell counts in AIDS patients, whereas LIG4 rs1805388 was linked to the clinical phases of AIDS patients. Conclusions. NHEJ gene polymorphisms can be considered to be risk factors of HIV-1 infection and AIDS progression in the northern Chinese MSM population. [ABSTRACT FROM AUTHOR]

Background: Previous studies reported that DNA damage repair (DDR) genes may play an important role in HIV-1 infection. The MRE11 gene, a member of the MRN complex, plays an essential part in the homologous recombination pathway, which is one of the classical DDR pathways. Previous reports have demonstrated that MRE11 has an effect on HIV-1 replication. However, the role of SNPs in the MRE11 gene and their impact on HIV-1 infection and AIDS progression remain unknown.Methods: In this study, 434 MSM HIV-1-infected patients in northern China and 431 age-matched healthy controls were enrolled. Five SNPs (rs2155209, rs10831234, rs13447720, rs601341 and rs11020803) at the MRE11 gene were genotyped. Another series of cases (409 MSM HIV-1-infected patients) and controls (403 age-matched healthy males) were recruited as the validation set.Results: In our study, rs10831234 showed differences in allele frequencies between cases and controls (P = 0.005). Additionally, there was an association between rs10831234 and HIV-1 infection susceptibility in dominant and additive models (P = 0.005 and P = 0.006, respectively). All significant associations were replicated in the validation set, and the associations were still significant after Bonferroni correction for multiple testing when the two data sets were combined. Furthermore, in haplotype association analyses between the case and control groups, the frequencies of the haplotypes Crs11020803Crs10831234 and Trs11020803Trs10831234 showed significant differences (P = 0.0181 and P = 0.0068, respectively).Conclusions: We demonstrated that the MRE11 rs10831234-T allele may confer increased risk of HIV-1 infection. [ABSTRACT FROM AUTHOR]

Men who have sex with men (MSM) are at high risk of HIV infection. The APOBEC3G (apolipoprotein B mRNA editing catalytic polypeptide 3G) protein is a component of innate antiviral immunity that inhibits HIV-1 replication. In the present study, a total of 483 HIV-1 seropositive men and 493 HIV-1 seronegative men were selected to investigate the association between single nucleotide polymorphisms (SNPs) of the APOBEC3G gene and susceptibility to HIV-1 infection and AIDS progression among MSM residing in northern China. Genotyping of four SNPs (rs5757465, rs3736685, rs8177832, and rs2899313) of the APOBEC3G was performed using the SNPscan™ Kit, while the rs2294367 polymorphism was genotyped using the SNaPshot multiplex system. Our results disclosed no association between the SNPs of APOBEC3G and susceptibility to HIV-1, or effects of these polymorphisms on the CD4 T cell count or clinical phase of disease. A meta-analysis of 1624 men with HIV-1 infection and 1523 controls suggested that the association between rs8177832 and susceptibility was not significant. However, we observed a trend towards association with HIV-1 infection for haplotype TTACA ( p = 0.082). The potential role of variants of APOBEC3G in HIV-1/AIDS warrants further investigation. [ABSTRACT FROM AUTHOR]