title: A allele of SNP12 in estrogen receptor 1 was a risk factor for cryptorchidism in Asians: a systematic review with meta-analysis and trial sequential analysis.
abstract: OBJECTIVE
  Some studies have been carried out to evaluate the association between SNP12 in estrogen receptor 1 and cryptorchidism, but the results remain inconsistent. We carried out a meta-analysis to explore the association between this polymorphism and cryptorchidism risk.
  
  
  METHODS
  All eligible studies were searched in PubMed, Web of Science, Embase and Cochrane Library. Pooled odds ratios, with 95 % confidence intervals, were assessed for the association using fixed- and random-effects models.
  
  
  RESULTS
  Overall, four case-control studies (363 cases, 415 controls) were included in the meta-analysis. No significant publication bias (P Begg = 0.308, P Egger = 0.288) was found. A allele of SNP12 in estrogen receptor 1 was protective factor to cryptorchidism in allele model, dominant genetic model and heterozygote comparison in Caucasians, but the result was turned out to be false positive by trial sequential analysis. However, A in allele model was risk factor to cryptorchidism in Asians (odds ratio 2.02, 95 % confidence interval 1.03-3.01, p = 0.946 for heterogeneity) and the result was turned out to be true positive by trial sequential analysis, even though there were merely two original studies.
  
  
  CONCLUSIONS
  The results of this meta-analysis suggest that A allele of SNP12 in estrogen receptor 1 may increase the risk of cryptorchidism in Asians. Meanwhile, further well-designed studies with large sample sizes are required to confirm the present findings, especially in Caucasians.
authors.affiliation: Department of Pediatric Surgery, Chengdu Women's and Children's Central Hospital, Chengdu, China.|Department of Urology Surgery, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorder, Key Laboratory of Pediatrics in Chongqing (CSTC2009CA5002), Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, No.136, Zhongshan 2 RD, Yuzhong District, Chongqing, 400014, China.
authors.forename: Changkai
authors.initials: C
authors.lastname: Deng
authors.affiliation: Chengdu Center for Disease Control and Prevention, Chengdu, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Dai
authors.affiliation: Department of Urology Surgery, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorder, Key Laboratory of Pediatrics in Chongqing (CSTC2009CA5002), Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, No.136, Zhongshan 2 RD, Yuzhong District, Chongqing, 400014, China.
authors.forename: Xuliang
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Urology Surgery, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorder, Key Laboratory of Pediatrics in Chongqing (CSTC2009CA5002), Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, No.136, Zhongshan 2 RD, Yuzhong District, Chongqing, 400014, China. 295969893@qq.com.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000483:Alleles; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D003456:Cryptorchidism / Q000235:genetics*; D047628:Estrogen Receptor alpha / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D016017:Odds Ratio; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012307:Risk Factors
chemical_list: D047628:Estrogen Receptor alpha
keywords: Cryptorchidism; Estrogen receptor alpha; Meta-analysis; Polymorphism