title: Impact of CAG repeat length in the androgen receptor gene on male infertility - a meta-analysis.
abstract: CAG repeats are polymorphic nucleotide repeats present in the androgen receptor gene. Many studies have estimated the association between CAG repeat length and male infertility, but the conclusions are controversial. Previous meta-analyses have come to different conclusions; however, new studies have been published. An updated meta-analysis was conducted. PubMed, CBM, CNKI and Web of Science databases were systematically searched for studies published from 1 January 2000 to 1 October 2015. Case-control studies on the association between CAG repeat length and male infertility using appropriate methodology were included. Forty studies were selected, including 3858 cases and 3161 controls. Results showed statistically significantly longer CAG repeat length among cases compared with controls (SMD = 0.14; 95% CI, 0.02-0.26). Shorter repeat length was associated with a lower risk of male infertility compared with a longer repeat length in the overall analysis (OR = 0.79, 95% CI: 0.66-0.95). Moreover, CAG repeat length was associated with male infertility in Caucasian populations, but not Asian or Egyptian populations. Subgroup analysis revealed no significant difference in German populations, but CAG repeat length was associated with male infertility in China and the USA. There were no significant differences between cases and controls in azoospermia and severe oligozoospermia.
authors.affiliation: The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China; Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Feifan
authors.initials: F
authors.lastname: Xiao
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Aihua
authors.initials: A
authors.lastname: Lan
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China; Department of Urology, Affiliated Hospital of Youjiang Medical College for Nationalities, Baise, Guangxi, China.
authors.forename: Zhidi
authors.initials: Z
authors.lastname: Lin
authors.affiliation: The Second Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China.
authors.forename: Jianfei
authors.initials: J
authors.lastname: Song
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Yuening
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Jiatong
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Urology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Kailong
authors.initials: K
authors.lastname: Gu
authors.affiliation: Department of Urology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Baihao
authors.initials: B
authors.lastname: Lv
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Urology Medical Research Center, Department of Guangxi Medical University Affiliated Hospital, Nanning, Guangxi, China.
authors.forename: Siping
authors.initials: S
authors.lastname: Zeng
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Ruoheng
authors.initials: R
authors.lastname: Zhang
authors.affiliation: First Clinical Academy, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.affiliation: First Clinical Academy, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Zhengyan
authors.initials: Z
authors.lastname: Pan
authors.affiliation: First Clinical Academy, Guangxi Medical University, Nanning, Guangxi, China.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Deng
authors.affiliation: Medical Scientific Research Center, Guangxi Medical University, Nanning, Guangxi, China. Electronic address: cncsyxl@126.com.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Yang
mesh_terms: D053713:Azoospermia / Q000208:ethnology / Q000235:genetics; D005006:Ethnicity; D006801:Humans; D007248:Infertility, Male / Q000208:ethnology / Q000235:genetics*; D008297:Male; D016017:Odds Ratio; D009845:Oligospermia / Q000208:ethnology / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics*; D018911:Trinucleotide Repeats
chemical_list: C410798:AR protein, human; D011944:Receptors, Androgen
keywords: CAG repeat; androgen receptor; male infertility; meta-analysis