GGN Repeat Length Research Articles

Polymorphic CAG and GGN repeats in Cryptorchidism patient risk: A meta-analytical study

Genetic mutations in the androgen receptor (AR) gene have been identified as the cause of androgen insensitivity syndrome. These mutations are linked to inconsistent development of the Wolffian duct and may result in conditions such as micropenis, hypospadias, and cryptorchidism. The androgen receptor has two polymorphic sites located in exon 1, which consists of varying amounts of CAG and GGN repeats. These repetitions lead to the formation of polyglutamine and polyglycine stretches of varied lengths. Increased CAG repeats lead to a decrease in androgen receptor transcriptional activity, but the impact of GGN triplets is less well understood. This research examined the CAG and GGN repeat lengths in males who had a past medical record of cryptorchidism. Prospective and retrospective observational studies from PubMed, Science Direct, and Embase were systematically searched up to 15th November 2020. Primary outcomes were analyzed using a fixed or random effect model regarding its heterogeneity and continued with multilevel modeling of each polymorphism and ethnicity. CAG and GGN repeat polymorphism was found to be significantly different compared to control in contributing to cryptorchidism (CAG: 0.55 [CI 95%=0.19-0.91]; p-value=0.003 and GGN 0.90 [CI95%=0.65-1.15]; p value<0.000). In conclusion, CAG and GGN repeat polymorphism have an essential role in the incidence of cryptorchidism.

Possible role of androgen receptor gene in therapeutic response of infertile men with hypogonadotropic hypogonadism

ABSTRACTHypogonadotropic hypogonadism (HH) is defined as a dysfunction of hypothalamic–pituitary–gonadal axis, which causes impairments in gametogenesis, pubertal maturation, and/or secretion of the gonadal sex hormones. Human chronic gonadotropin (hCG) stimulates the Leydig cells of the testis to secrete testosterone, which is essential for spermatogenesis. Testosterone replacement therapy is one of the possible options to manage HH treatment. Given the fact that testosterone functions are mediated via androgen receptor (AR), the aim of the present study was to evaluate whether the CAG/GGN triple repeat expansion in AR gene can modulate the response to hCG and testosterone treatment in HH men. Sixty-two men who diagnosed with HH and treated with testosterone and hCG were assessed after treatment. They were classified into two groups, 31 subjects with a positive and 31 subjects with a negative response to replacement therapy within 12–18 months. Androgen receptor CAG and GGN repeat numbers were measured in both groups by hot start polymerase chain reaction (PCR)-sequencing technique. Subjects who reached complete spermatogenesis showed the 20 and 23 as the median numbers of AR CAG/GGN repeats, respectively. In individuals who did not respond to treatment the median length for both CAG/GGN repeats were 23. The average of CAG repeats was statistically lower in patients who had the positive response in comparison to patients who did not respond to hormone therapy (p < 0.05), but the length of GGN repeats were not statistically different between these groups of patients (p > 0.05). The number of CAG repeats are negatively and significantly associated with better hormone therapy response. Our results suggest that the length of CAG repeat polymorphism in AR gene might affect the response to treatment in men suffering from HH, whereas no relationship was found between AR gene GGN repeat polymorphism and testosterone and hCG replacement therapy response.Abbreviations: AR: androgen receptor; FSH: follicle stimulating hormone; Gn: gonadotropins; GnRH: gonadotropin-releasing hormone; hCG: human chronic gonadotropin; HH: hypogonadotropic hypogonadism; LH: luteinizing hormone; PCR: polymerase chain reaction

Study of trinucleotide expansions and expression of androgen receptor in infertile men with abnormal spermogram referred to Royan institute.

Androgen receptor (AR) mediates androgen activities such as the growth of accessory sex organs, and initiation and promotion of spermatogenesis. There are two trinucleotide polymorphisms (CAG and GGN repeats) in the first exon of AR gene that their association with infertility is still controversial. The variants of both polymorphic repeats were investigated by PCR-Sequencing in 220 infertile men (80 azoospermic, 60 oligospermic and 80 asthenospermic) and 80 healthy fertile controls. AR Expression level was quantified by RT-qPCR on 30 patients (20 patients with nonobstructive azoospermia (NOA) and 10 obstructive azoospermia patients as controls). Our results demonstrated that the medians of CAG and GGN repeats length in infertile group were significantly higher than fertile men (p<0.05). AR expression results showed a significant increase in SCOS group compared to control (p<0.05). Long stretches of tandem repeats of AR gene may negatively affect the function of the gene and consequently lead to male infertility. In patients with SCOS, AR expression increases because of the lack of germ cells. Therefore, with increasing AR expression, the probability of SCOS occurrence is also increased. It can be concluded that increasing AR expression in testes tissue decreases the probability of sperm presence.

E relation between isolated micropenis in childhood with CAG and GGN repeat polymorphisms in the androgen receptor gene

Background/aim: In micropenis cases accompanied by external genital abnormalities such as hypospadias and cryptorchidism, infertility and spermatogenic failures have been reported to correlate with androgen receptor ( AR ) gene CAG and GGN repeat polymorphisms. While there is one study on isolated micropenis and CAG repeats, no study related to GGN repeats has been reported. We investigated the relation between CAG and GGN repeats in the AR gene with development of penis length in boys with isolated micropenis. Materials and methods: A total of 24 Turkish boys with isolated micropenis (<–2.5 SD) and 64 healthy controls who had normal basal serum gonadotropin levels were examined. Genotyping was performed by DNA sequencing of the patients and controls. Results: The distribution of CAG and GGN repeat lengths in our patients and controls was within the normal range and did not significantly differ between the patients and the controls. Conclusion: CAG repeat length in the AR constitutes one of multiple genetic factors relevant to the development of isolated micropenis, and the expansion of this repeat can be detected as a likely modifying factor. Moreover, the interactions of other genes that may be involved in the etiology of isolated micropenis with CAG and GGN repeats have to be taken into consideration.

Association of androgen receptor gene CAG and GGN repeat polymorphism with cryptorchidism: A meta-analysis.

Researches on association between variations in the androgen receptor (AR) gene repeat polymorphisms and cryptorchidism (CO) had conflicting results. The aim of this meta-analysis was to analyse the potential effects of AR CAG and/or GGN repeat polymorphism on CO. Studies were independently appraised by two investigators on PubMed, Web of Science, EBSCO databases and Foreign Medical Retrieval System. Case-control studies with measurement of CAG and/or GGN repeat length were included. Weighted mean difference (WMD) and 95% confidence intervals (CIs) for the CAG or GGN repeat polymorphism and CO were calculated. Five reports were included in this analysis. Overall, no difference was identified between patients and fertile men in CAG repeat length. However, when the CO was divided into unilateral and bilateral, longer CAG repeat region was significantly associated with CO in bilateral group (WMD=0.74; 95% CI, 0.01-1.47; p<.05). In addition, GGN lengths were significantly higher in patients compared with those in controls (WMD=1.17; 95% CI, 0.28-2.06; p<.05). No obvious effect was found in the GGN length when compared unilateral or bilateral group with control respectively. The results in this meta-analysis indicated that AR CAG and GGN repeat polymorphisms may be an important pathogenesis of CO.

Androgen receptor gene polymorphisms and maximal fat oxidation in healthy men. A longitudinal study.

Androgens play a major role in fat oxidation; however, the effects of androgens depend, among other factors, on the intrinsic characteristics of the androgen receptor (AR). Lower repetitions of CAG and GGN polymorphism appear to have a protective effect on fat accumulation in the transition from adolescent to mid-twenties. Whether a similar protective effect is present later in life remains unknown. The aims of this study were: a) to evaluate if extreme CAG and GGN repeat polymorphisms of the androgen receptors influence body fat mass, its regional distribution, resting metabolic rate (RMR), maximal fat oxidation capacity (MFO) and serum leptin, free testosterone and osteocalcin in healthy adult men; and b) to determine the longitudinal effects on fat tissue accumulation after 6.4 years of follow-up. CAG and GGN repeats length were measured in 319 healthy men (mean ± standard deviation [SD]: 28.3 ± 7.6 years). From these, we selected the subjects with extreme short (CAGS < or equal 19; n = 7) and long (CAGL > or equal 24; n = 10) CAG repeats, and the subjects with short (GGNS < or equal to 22; n = 9) and long (GGNL > or equal to 25; n = 10) GGN repeats. Body composition was assessed by DXA and serum levels of leptin, free testosterone and osteocalcin by ELISA. After 6.4 years of follow-up, DXA was repeated, and resting metabolic rate (RMR), MFO and VO2max determined by indirect calorimetry. CAGS and CAGL subjects had similar RMR and accumulated comparable amounts of fat tissue over 6.4 ± 1.0 years of follow-up. However, CAGL had higher MFO and total lean mass than CAGS(p < 0.05). Men with GGNSaccumulated greater amount of total fat mass than men with GGNL, particularly in the trunk region seven years later. This concurred with a greater MFO in the GGNLgroup (p < 0.05), who accumulated less fat mass. Free testosterone was associated with MFO in absolute values (r = 0.45; p < 0.05) and MFO per kg of lower extremity lean mass per height squared (r = 0.35; p < 0.05). CAG and GGN repeat polymorphisms may influence muscle fat oxidation capacity and may have a role in the accumulation of fat over the years.

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

// Yongxiang Shi 1 , Weishan Chen 1 , Qinghuai Li 2 , Zhaoming Ye 1 1 Department of Orthopaedic Surgery, 2nd Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China 2 Department of Medicine, 3rd Hospital of Henan Province, Henan, China Correspondence to: Zhaoming Ye, email: ye_zhaoming@163.com Keywords: osteosarcoma, papillary thyroid cancer, AR, repeat, CAG Received: May 24, 2016 Accepted: August 13, 2016 Published: September 08, 2016 ABSTRACT The androgen receptor ( AR ) is involved in the differentiation and growth of many cancers. We hypothesized that two microsatellite polymorphic variants, AR (CAG)n and (GGN)n repeats, were also associated with the development of Papillary thyroid cancer (PTC) and Osteosarcoma. In current study, we conducted two case-control studies in a Chinese population to investigate the possible relationship between these two AR repeat polymorphisms and the risk of PTC and Osteosarcoma. The AR CAG repeat length was significantly associated with both risk of PTC and Osteosarcoma. Subjects with shorter AR CAG repeats had a higher risk of developing PTC (OR = 1.47, 95% CI: 1.17–1.85, P = 0.001) and Osteosarcoma (OR = 1.53, 95% CI: 1.19–1.97, P = 9.2 x 10 –4 ). Specifically, shorter GGN repeats also contribute a significant increased risk of Osteosarcoma (OR = 1.35, 95% CI: 1.03–1.77, P = 0.030). Our results contribute to a better understanding of the complex hormone related mechanisms underlying PTC and Osteosarcoma.

The number of CAG and GGN triplet repeats in the Androgen Receptor gene exert combinatorial effect on hormonal and sperm parameters in young men.

Androgen receptor (AR) is a transcription factor that is activated upon binding to testosterone (T) and is implicated in regulating the expression of reproduction-related genes. The human AR gene (Xq11-12) spans 186,588bp and eight exons. N-terminal transactivation domain of the encoded AR protein harbours two polymorphic stretches of identical amino acids, a polyglutamine tract (encoded by 8-37 CAG-repeats) and a polyglycine tract (encoded by 10-30 GGN-repeats). We set forward to analyse independent and combinatory effects of the length of these repetitive tracts on male reproductive hormones, testicular and sperm parameters in a population-based cohort of Baltic young men (n=974; aged 20.1±2.1years). We designed an assay to amplify and detect simultaneously the variants of both polymorphic repeats. The study revealed that elongated AR CAG tract was associated with lower FSH (linear regression: p=0.0002, effect per repeat -0.056 IU/L). As a novel finding, the carriers of GGN-stretch with ≥24 repeats showed a trend for decreased sperm concentration (p=0.027). Although neither of the variants exhibited an isolated effect on circulating T, their allelic combinations modulated serum T levels, as well as sperm concentration. The lowest T was measured for men carrying the AR gene with long CAG (n≥25) and short GGN (n≤21) repeat tracts (mean 18.8 vs. 25.5-28.6 nmol/L for the other AR variants, p=0.017). The lowest sperm concentration was detected among individuals with both elongated repetitive stretches (CAG, n≥25 and GGN, n≥24; mean 49.0 vs. 68.4-72.1 mill/mL for the other variants; p=0.00059). The innovative study design enabled to clearly demonstrate a combinatory impact of CAG and GGN repeat lengths at male reproductive parameters. As AR regulates transcription of over 900 genes in many tissues and organs, the combinatory effects of these common repeat-length variants on male physiology in the wider context and across lifetime are still to be assessed.

Androgen receptor gene CAG and GGN repeat lengths as predictors of recovery of spermatogenesis following testicular germ cell cancer treatment.

Spermatogenesis is an androgen-regulated process that depends on the action of androgen receptor (AR). Sperm production may be affected in men treated for testicular cancer (TC), and it is important to identify the factors influencing the timing of spermatogenesis recovery following cancer treatment. It is known that the CAG and GGN repeat numbers affect the activity of the AR; therefore, the aim of this study is to investigate if the CAG and GGN polymorphisms in the AR gene predict recovery of sperm production after TC treatment. TC patients (n = 130) delivered ejaculates at the following time points: postorchiectomy and at 6, 12, 24, 36, and 60 months posttherapy (T0, T6, T12, T24, T36, and T60). The CAG lengths were categorized into three groups, <22 CAG, 22–23 CAG, and >23 CAG, and the GGN tracts were also categorized into three groups, <23 GGN, 23 GGN, and >23 GGN. At T12, men with 22–23 CAG presented with a statistically significantly (P = 0.045) lower sperm concentration than those with other CAG numbers (8.4 × 106 ml−1 vs 16 × 106 ml−1; 95% CI: 1.01–2.65). This association was robust to omitting adjustment for treatment type and sperm concentration at T0 (P = 0.021; 3.7 × 106 ml−1 vs 10 × 106 ml−1; 95% CI: 1.13–4.90). The same trends were observed for total sperm number. The least active AR variant seems to be associated with a more rapid recovery of spermatogenesis. This finding adds to our understanding of the biology of postcancer therapy recovery of fertility in males and has clinical implications.

Shorter GGN Repeats in Androgen Receptor Gene Would Not Increase the Risk of Prostate Cancer.

The association between the polymorphic GGN repeat in androgen receptor gene and prostate cancer susceptibility has been studied extensively. But the results of these polymorphisms with prostate cancer risk remain inconclusive. Previous meta-analysis showed short GGN repeats (≤16 repeats) had high risks for prostate cancer compared with longer GGN repeats (>16 repeats). Many studies have been published since the release of the previous meta-analysis. Here, we conducted an updated meta-analysis to demonstrate whether short repeats have higher risks for prostate cancer compared to long repeats. Five databases (PubMed, EMBASE, Cochrane Library, The China National Knowledge Infrastructure, and Web of Science) were last searched until January 1, 2016. Random- or fixed-effects model was performed based on the heterogeneity among studies. The potential publication bias was assessed via Begg funnel plot and Egger regression test. Twelve out of 157 studies were extracted. The result indicated that there was no significant difference between short repeat group and long repeat group in the overall analysis ( I2 = 80.6%, P = .000, odds ratio = 1.31, 95% confidence interval: 0.93-1.83). There was no association between the length of GGN repeats and the occurrence of prostate cancer in both Caucasian and African American ( I2 = 6.7%, P = .359, odds ratio = 1.11, 95% confidence interval: 0.94-1.32; and I2 = 74.1%, P = .050, odds ratio = 0.963, 95% confidence interval: 0.36-2.58). Our result demonstrated that a shorter GGN repeat polymorphism cannot increase the risk of prostate cancer compared to the longer GGN repeats. That's different with previous meta-analysis.

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

The androgen receptor (AR) is involved in the differentiation and growth of many cancers. We hypothesized that two microsatellite polymorphic variants, AR (CAG)n and (GGN)n repeats, were also associated with the development of Papillary thyroid cancer (PTC) and Osteosarcoma. In current study, we conducted two case-control studies in a Chinese population to investigate the possible relationship between these two AR repeat polymorphisms and the risk of PTC and Osteosarcoma. The AR CAG repeat length was significantly associated with both risk of PTC and Osteosarcoma. Subjects with shorter AR CAG repeats had a higher risk of developing PTC (OR = 1.47, 95% CI: 1.17–1.85, P = 0.001) and Osteosarcoma (OR = 1.53, 95% CI: 1.19–1.97, P = 9.2 × 10–4). Specifically, shorter GGN repeats also contribute a significant increased risk of Osteosarcoma (OR = 1.35, 95% CI: 1.03–1.77, P = 0.030). Our results contribute to a better understanding of the complex hormone related mechanisms underlying PTC and Osteosarcoma.

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

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.

Androgen receptor gene polymorphism influence fat accumulation: A longitudinal study from adolescence to adult age.

To determine the influence of androgen receptor CAG and GGN repeat polymorphisms on fat mass and maximal fat oxidation (MFO), CAG and GGN repeat lengths were measured in 128 young boys, from which longitudinal data were obtained in 45 of them [mean ± SD: 12.8 ± 3.6 years old at recruitment, and 27.0 ± 4.8 years old at adult age]. Subjects were grouped as CAG short (CAGS ) if harboring repeat lengths ≤ 21, the rest as CAG long (CAGL ); and GGN short (GGNS ) if GGN repeat lengths ≤ 23, or long if > 23 (GGNL ). CAGS and GGNS were associated with lower adiposity than CAGL or GGNL (P < 0.05). There was an association between the logarithm of CAG repeats polymorphism and the changes of body mass (r = 0.34, P = 0.03). At adult age, CAGS men showed lower accumulation of total body and trunk fat mass, and lower resting metabolic rate (RMR) and MFO per kg of total lean mass compared with CAGL (P < 0.05). GGNS men also showed lower percentage of body fat (P < 0.05). In summary, androgen receptor CAG and GGN repeat polymorphisms are associated with RMR, MFO, fat mass, and its regional distribution in healthy male adolescents, influencing fat accumulation from adolescence to adult age.

ANDROGEN RECEPTOR CAG AND GGN REPEAT POLYMORPHISMS AND BONE MASS IN BOYS AND GIRLS.

the human androgen receptor (AR) gene possesses two trinucleotide polymorphic repeats, (CAG and GGN) that affect the amount of AR protein translated. In this study, we genotyped these polymorphic tracts in a representative sample of Caucasian children (Tanner ≤ 5), 152 boys (11.5 } 2.6 yrs) and 116 girls (10.1 } 3.2 yrs) from Spain and investigated their association with bone mass. the length of CAG and GGN repeats was determined by PCR and fragment analysis. Body composition was assessed by dual energy x-ray absorptiometry (DXA). Individuals were grouped as CAG short (CAGS) if harboring repeat lengths of ≤ 21 and CAG long (CAGL) if CAG > 21. Moreover, subjects were grouped as GGN short (GGNS) if harboring repeat lengths of ≤ 23 and GGN long (GGNL) if GGN > 23. in boys, significant differences in height, body mass, whole body bone mineral density (BMD) and content (BMC), upper extremities BMC, lower extremities BMC, femoral neck BMD, Ward's triangle BMC and BMD and lumbar spine BMD were observed between CAGS and CAGL groups (P < 0.05). Thus, upper extremities BMD differed between GGNS and GGNL groups. After adjusting for confounding variables, only upper extremities BMD between GGNS and GGNL groups remained significant (P < 0.05). No differences were observed in girls in any measured site in relation to either CAG or GGN polymorphisms length. our results support the hypothesis that longer alleles of the AR CAG and GGN polymorphisms are associated with increased bone mass in prepubertal boys.

Androgen receptor CAG and GGN repeat polymorphisms influence performance in boys and girls.

Shorter CAG and GGN androgen receptor (AR) repeat polymorphisms are associated with stronger androgen signaling, and therefore, could influence lean mass and exercise performance during growth. Physical fitness and body composition were measured by standardized procedures and the length of CAG and GGN repeats was determined by PCR and fragment analysis in 152 boys (11.5±2.6 years; Tanner ≤5) and 116 girls (10.1±3.2 years; Tanner ≤5). Individuals were grouped as CAG short (CAGS) if harboring repeat lengths of ≤21 and CAG long (CAGL) if CAG >21. Moreover, subjects were grouped as GGN short (GGNS) if harboring repeat lengths of ≤23 and GGN long (GGNL) if GGN>23. No significant differences in anthropometrics and body composition were observed between either CAGS and CAGL groups and GGNS and GGNL groups. Boys harboring CAGS completed the 300-meter test faster than their CAGL counterparts. Moreover, girls from the GGNL group showed a significant higher VO2max than those in the GGNS group. In summary, carrying a short allele of the androgen receptor CAG repeat polymorphism is associated to higher anaerobic performance in boys, whereas long alleles of androgen receptor GGN polymorphisms are associated to higher aerobic capacity in girls.

Polymorphism of CAG and GGN repeats of androgen receptor gene in women with polycystic ovary syndrome

One characteristic of polycystic ovary syndrome (PCOS) is hyperandrogenism, which may be related to the activity of androgen receptor (AR). This study was designed to investigate the polymorphism of CAG and GGN repeats in the AR gene in women with PCOS. The frequency distributions of CAG and GGN repeat alleles, as well as their X-inactivation patterns, were compared between 76 age-matched normal women (control group) and 80 women with PCOS (PCOS group). The expression of AR mRNA in the ovarian tissues of seven patients with PCOS and five normal women was also tested using real-time quantitative PCR. It was found that PCOS patients had significantly higher frequency of longer GGN biallelic mean (29.8%) and X-weighted biallelic mean (33.3%) than controls (6.1% and 3.2%, respectively, P = 0.002, P = 0.003). The odds ratio of the long GGN repeat length (n > 16) before and after X-chromosome inactivation (XCI) in the PCOS group was significantly higher than in controls (P = 0.0001, P = 0.005). AR-GGN repeat mRNA expression was higher in the ovarian tissue of controls compared with PCOS patients (P = 0.022). In conclusion, the data suggest that the GGN repeat polymorphism in the AR gene is associated with PCOS.

Non-linear association between androgen receptor CAG and GGN repeat lengths and reproductive parameters in fertile European and Inuit men

Recently the dogma that there is an inverse linear association between androgen receptor (AR) CAG and GGN polymorphisms and receptor activity has been challenged. We analysed the pattern of association between 21 male reproductive phenotypes and AR CAG/GGN repeat lengths in 557 proven-fertile men.A linear association was only found between sperm DNA fragmentation index (DFI) and CAG length, and between inhibin B and GGN length. Men with longer CAG then the reference (22–24), had higher oestradiol levels, whereas men with shorter CAG stretches had a higher DFI and a higher proportion of Fas-positive germ cells. Subjects with either short or long CAG had increased seminal levels of prostate-specific antigen and neutral α-glucosidase activity. Compared to men with the median GGN length of 23, those with shorter GGN repeats had higher levels of inhibin B, higher proportions of normal and progressive sperm, and a higher fraction of Fas-positive sperm, while men with longer GGN had higher oestradiol levels.These data indicate that at least for some markers of male reproductive function the association with CAG or GGN repeat length is curvilinear.

Androgen Receptor Gene Polymorphisms and the Fat‐Bone Axis in Young Men and Women

Androgen receptor (AR) CAG(n) (polyglutamine) and GGN(n) (polyglycine) repeat polymorphisms determine part of the androgenic effect and may influence adiposity. The association of fat mass, and its regional distribution, with the AR CAG(n) and GGN(n) polymorphisms was studied in 319 and 78 physically active nonsmoker men and women (mean ± SD: 28.3 ± 7.6 and 24.8 ± 6.2 years old, respectively). The length of CAG and GGN repeats was determined by polymerase chain reaction and fragment analysis, and confirmed by DNA sequencing of selected samples. Men were grouped as CAG short (CAG(S)) if harboring repeat lengths ≤ 21, the rest as CAG long (CAG(L)). The corresponding cutoff CAG number for women was 22. GGN was considered short (GGN(S)) if GGN ≤ 23, the rest as GGN long (GGN(L)). No association between AR polymorphisms and adiposity or the hormonal variables was observed in men. Neither was there a difference in the studied variables between men harboring CAG(L) + GGN(L),CAG(S) + GGN(S),CAG(S) + GGN(L), and CAG(L) + GGN(S) combinations. However, in women, GGN(n) was linearly related to the percentage of body fat (r = 0.30, P < .05), the percentage of fat in the trunk (r = 0.28, P < .05), serum leptin concentration (r = 0.40, P < .05), and serum osteocalcin concentration (r = 0.32, P < .05). In men, free testosterone was inversely associated with adiposity and serum leptin concentration, and positively with osteocalcin, even after accounting for differences in CAG(n), GGN(n), or both. In summary, this study shows that the AR repeat polymorphism has little influence on absolute and relative fat mass or its regional distribution in physically active men. In young women, GGN length is positively associated with adiposity, leptin, and osteocalcin.

CAG and GGN Repeat Length Polymorphisms of Androgen Receptor Gene in Women with Breast Cancer: A Case-Control Study from South India

Aim: The Androgen Receptor (AR) is a ligand-dependent transcriptional activator and the AR gene contains a highly polymorphic trinucleotide repeat CAG and GGN in the first exon. Given the lack of information AR-CAG and GGN repeat polymorphism and its potential correlation with breast cancer in South Indian women, we conducted a case-control study to observe the effects of CAG & GGN repeat length polymorphism and risk of breast cancer. Methods: Polymorphisms for AR-CAG and GGN repeat length was detected by Gene Scan analysis in the genomic DNA from cases with breast cancer and controls. Results: Association between AR genotype was calculated by categorising alleles as short (S) and long (L) and taking median value as the cut-off. LL genotype of CAG repeat was found to be associated with breast cancer (OR, 4.58; 95% CI, 10.61-1.98; p—0.0004). GGN repeat having ≥21 was found in most of the cases and none of the cases showed 20 repeats thus indicate that alleles having homozygous repeat 20 may be protective towards breast cancer. Also, SS genotype was observed in 56.84% of cases and in 73.03% of controls (OR, 0.48; 95% CI, 0.26-0.89; p value, 0.02). Conclusion: Our results indicate that longer CAG and GGN repeat may be associated with breast cancer whereas, the shorter GGN repeat length genotype of AR are protective.

Association of androgen receptor gene, CAG and GGN repeat length polymorphism and impulsive-disinhibited personality traits in inmates

This study analyses the association between impulsive-disinhibited personality traits and the androgen receptor CAG and GGN repeat polymorphisms in both inmates and control samples. We used two samples: 153 inmates (mean age= 33.31 years; standard deviation: 8.6; range: 20-63) and 108 controls (mean age= 26.71 years; standard deviation: 9.68; range: 17-53). A disinhibited personality construct was measured using the following personality scales: Sensation Seeking, Aggression-Hostility, Psychoticism, Sensitivity to Reward, Novelty Seeking and Impulsivity. A factor analysis of the six scales provided a normalized z index that was taken as a measure of impulsive-disinhibited personality. Our data show that inmates carrying CAG short and GGN long haplotype group (short-long haplotype) obtained higher scores on all personality scales. Differences were found for the Impulsive Sensation-Seeking scale (age-adjusted multivariate analysis, P<0.016) and z index (P<0.036). When comparing extreme groups in the impulsive-disinhibited personality index (taking the 75th percentile as a cut-off), carriers of the short-long haplotype were more prevalent in the extreme high group (30 vs. 10%: unadjusted odds ratio=3.8; 95% confidence interval=1.5-9.8; age-adjusted odds ratio=4.4; 95% confidence interval=1.6-12; P<0.004). Our findings suggest that the androgen receptor CAG and GGN polymorphisms might influence impulsive-disinhibited personality traits.