Association between androgen receptor gene CAG repeat polymorphism and breast cancer risk: a meta-analysis

Abstract

Androgens have been hypothesized to influence risk of breast cancer through several possible mechanisms, including their conversion to estradiol and their binding to the estrogen receptor and/or androgen receptor (AR) in the breast. The CAG repeat polymorphism in AR exon 1 has been implicated in breast cancer risk; however, studies on the association between this polymorphism and breast cancer risk remain conflicting. In order to derive a more precise estimation of the relationship, a large population-based case-control study was performed. We found that a long CAG sequence has a protective effect on breast cancer using an a priori determined cutoff (< 22 or ≥ 22) in a dominant model analysis [SL-LL vs. SS, odds ratio (OR) = 0.86, 95% confidence intervals (CI): 0.67-1.10]. A similar result was obtained by analyzing seven detailed genotyping case-control studies by allele comparison in dominant and recessive models. However, larger scale primary study is required to further evaluate the interaction of AR CAG polymorphism and breast cancer risk.

Androgen receptor CAG and GGN repeat length variation contributes more to the tumorigenesis of osteosarcoma

“…While compared to those with the longer (> 23) GGN repeat length, subjects in the category of shorter (≤ 23) GGN repeats had a significant increased risk of Osteosarcoma (OR = 1.35, 95% CI: 1.03–1.77, P = 0.030). These findings were consistent with previous studies about epithelial ovarian cancer [23, 24], TMPRSS2:ERG-positive prostate cancer [25], breast cancer [26, 27], prostate cancer [28], and so on. Major strength of the current study was the large sample size to minimize type I error.…”

The Spectrum of Genetic Mutations in Breast Cancer

“…Several studies have tried to evaluate the relationship between the number of CAG repeats in the gene and the risk of developing breast cancer in women. However, their attempts have yielded conflicting results (Hao et al, 2010). Some studies suggest that an increased number of CAG repeat in the region augments breast cancer risk in women.…”

Androgen receptor CAG and GGN polymorphisms in boys with isolated hypospadias

“…In accordance with these observations, several studies have described associations between shorter or longer CAG repeat lengths and some androgen-related diseases, such as Kennedy ' s disease (28 -30) and prostate (31,32) and breast (33,34) cancer. Nevertheless, the length of this polymorphism has not been related with androgen physiological effects, such as muscle mass and physical fi tness, in young healthy men (35) , suggesting that the length of this polymorphism may have an important impact in the development of some pathological conditions directly (in cases where the CAG length is extremely long, e.g., Kennedy ' s disease) or indirectly by interacting with other genetic and/or endocrine factors, whereas its impact over androgenic function in healthy men is less clear.…”