Predictive value of GGN and CAG repeat polymorphisms of androgen receptors in testicular cancer: a meta-analysis.

Weijun Jiang,Qiuyue Wu,Qing Zhou,Shuaimei Liu,Peiran Zhu,Weiwei Li,Jing Zhang,Mengxia Ni,Xinyi Xia,Mingchao Zhang

doi:10.18632/oncotarget.7337

Abstract

The risk of testicular cancer (TC) is markedly increased in subjects with androgen insensitivity, and previous studies have proposed that GGN and CAG repeats in androgen receptors (AR) could be related to the risk of TC. To evaluate the association between the length of GGN and CAG repeats in AR and TC, a meta-analysis involving 3255 TC cases and 2804 controls was performed. The results suggested that long GGN repeats are associated with an increased risk of TC compared with those < 23 [odds ratio (OR) = 1.22, 95% confidence interval (CI) = 1.05–1.41]; similarly, a subgroup analysis revealed that this association occurred in studies with case sizes > 200, and in the mid-latitude, and seminoma subgroups. The subgroup analysis based on populations, high-latitude, and seminomas/non-seminomas suggested that AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats might confer a protective effect to the patients with TC (in the high-latitude subgroup analysis, for > 25 vs. 21–25: OR = 0.54, 95% CI = 0.41–0.70). In contrast, an increased risk of TC was observed for AR CAG repeat polymorphisms with > 25 and < 21 + > 25 repeats in the mid-latitude subgroup (for > 25 vs. 21–25: OR = 1.65, 95% CI = 1.09–2.50). In addition, no associations between the remaining subgroups and male infertility were observed. In short, this meta-analysis suggested that AR GGN and CAG repeat polymorphisms may be involved in the etiology of TC.

Highlights

Testicular cancer (TC) is an malignancy, accounting for 1%–2% of all tumors among men worldwide [1], and affects primarily young men in the age group 15–44 years
Our results indicated that long GGN repeats were associated with an increased risk of TC, compared with repeats < 23; sample size > 200 and the mid-latitude and seminoma subgroups were associated with an increased risk of TC
androgen receptors (AR) CAG repeat polymorphism with > 25 and < 21 + > 25 repeats may confer a protective effect to the TC patients in the analysis of the PB, high-latitude, seminoma, and non-seminoma subgroups

Summary

Introduction

Testicular cancer (TC) is an malignancy, accounting for 1%–2% of all tumors among men worldwide [1], and affects primarily young men in the age group 15–44 years. Some studies have attempted to evaluate the www.impactjournals.com/oncotarget association between CAG and GGN repeat number and the risk of TC [6, 9, 10, 12,13,14,15]; the results appear contradictory because of differences in the sources of the study participants and inconsistencies in the inclusion criteria in case and control subjects among the studies [9, 16]. To the best of our knowledge, to date, no metaanalysis has analyzed the results of all the studies that evaluated this association This meta-analysis was conducted to investigate the association between CAG and GGN repeat polymorphisms and the risk of TC, as well as the genetic heterogeneity across different control sources and study designs. Seven reports involving 3255 TC cases and 2804 controls were identified according to the inclusion criteria for the pooled analysis

Methods

Results

Conclusion