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The association between alcohol dehydrogenase 1C (ADH1C) gene polymorphism and alcoholic liver cirrhosis (ALC) has been analyzed in several studies, but results have been conflicting. In this study, a meta-analysis was performed to assess the associations between the ADH1C polymorphism and risk of ALC. Relevant studies were identified using PubMed, Web of Science, CNKI and Wanfang databases up to January 10, 2015. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the association using the fixed or random effect model. A total of 16 case-control studies, including 1375 cases and 1802 controls, were included. Overall, no significant association between the ADH1C polymorphism and ALC risk was found (dominant model: OR=0.87, 95% CI: 0.62-1.23; recessive model: OR=1.30, 95% CI: 0.84-1.99; *1/*2 vs. *1/*1: OR=0.87, 95% CI: 0.63-1.21; *2/*2 vs. *1/*1: OR=1.10, 95% CI: 0.71-1.70). In the subgroup analysis by ethnicity, we observed a significant association in Asian descent (*1/*2 vs. *1/*1: OR=1.63, 95% CI: 1.07-2.49), while a decreased risk was found among Caucasians (dominant model: OR=0.81, 95% CI: 0.66-0.99; *1/*2 vs. *1/*1: OR=0.76, 95% CI: 0.61-0.95). This meta-analysis demonstrated that the ADH1C polymorphism might increase the risk of ALC in Asians, while it may be a protective factor for ALC among Caucasians.

The alcohol dehydrogenase 2 (ADH2) gene has been implicated in the development of alcoholic liver cirrhosis (ALC). However, the results are inconsistent. In this study, a meta-analysis was performed to assess the associations between the ADH2 polymorphism and the risk of ALC. Relevant studies were retrieved by searching PubMed, Web of Science, CNKI, Wanfang and VIP databases up to January 10, 2015. The pooled odds ratio (OR) with a 95% confidence interval (CI) was calculated using the fixed- or random effects model. A total of 21 case-control studies included 1812 cases and 3468 controls were included. Overall, the ADH2 polymorphism was associated with a decreased risk of ALC in all four genetic models (dominant model: OR=0.56, 95% CI: 0.38-0.83; recessive model: OR=0.59, 95% CI: 0.39-0.91; *1/*2 vs. *1/*1: OR=0.58, 95% CI: 0.40-0.85; *2/*2 vs *1/*1: OR=0.35, 95% CI: 0.16-0.75). Besides, in stratification analysis by ethnicity, similar results were observed in Asian populations, however, we detected no association in Caucasian populations under recessive and homozygote comparison model. The pooled evidence suggests that ADH2 polymorphism may be an important protective factor for alcoholic liver cirrhosis, especially for Asians.

The polymorphisms in the three main heat shock protein 70 (HSP70-1, HSP70-2, and HSP70-hom) genes were identified to be associated with cancer risk. However, the results are inconsistent. We perform a meta-analysis to evaluate the association between the three HSP70 polymorphisms and cancer risk. Relevant studies were identified using PubMed, Web of Science, Chinese National Knowledge Infrastructure (CNKI), and Wanfang databases up to March 29, 2014. The cancer risk associated with the HSP70 polymorphisms was estimated for each study by odds ratios (OR) together with its 95% confidence interval (CI), respectively. Twenty case-control studies from eighteen publications were included; a significant association was observed for HSP70-2 polymorphism (dominant model: OR = 1.53, 95% CI: 1.11–2.09; recessive model: OR = 1.91, 95% CI: 1.06–3.45; AG versus AA: OR = 1.38, 95% CI: 1.03–1.84; GG versus AA: OR = 2.34, 95% CI: 1.21–4.54), while there was no significant association for HSP70-1 and HSP70-hom polymorphisms. Besides, in stratification analyses by ethnicity, cancer type, and source of control, significant association was detected for HSP70-2 polymorphism, while for HSP70-hom polymorphism, we found a significant association in hospital-based population under homozygote comparison model. This meta-analysis suggests that the HSP70-2 polymorphism rather than HSP70-hom and HSP70-1 polymorphisms was associated with the risk of cancer.