The present study was carried out to assess the role of androgen receptor CAG repeat polymorphism and X chromosome inactivation (XCI) pattern among Indian PCOS women and controls which has not been hitherto explored and also to test the hypothesis that shorter CAG alleles would be preferentially activated in PCOS. CAG repeat polymorphism and X chromosome methylation patterns were compared between PCOS and non-PCOS women. 250 PCOS women and 299 controls were included for this study. Androgen receptor CAG repeat sizes, XCI percentages, and clinical and biochemical parameters were measured. The mean CAG repeat number is similar between the cases (18.74±0.13) and controls (18.73±0.12). The obese PCOS women were significantly more frequent in the <18 and >20 CAG repeat category than the lean PCOS women, yielding a highly significant odds (p = 0.001). Among the women with non-random X-inactivation, alleles with <19 repeats were more frequently activated among cases than controls (p = 0.33). CAG repeat polymorphism by itself cannot be considered as a useful marker for discriminating PCOS. We observed a trend of preferential activation of the shorter allele among the PCOS cases with non random XCI pattern. In the obese PCOS women, this microsatellite variation may account for the hyperandrogenicity to a larger extent than the lean PCOS women.
An increased frequency of skewed X-chromosome inactivation (XCI) is found in clinically overt autoimmune thyroid disease (AITD) compared with controls. Whether skewed XCI is involved in the pathogenesis of autoantibodies to thyroid peroxidase (TPOAb) in euthyroid subjects is unknown. To examine the impact of XCI on the serum concentration of TPOAb, we studied whether within-cohort and within-twin-pair differences in XCI are associated with differences in serum concentrations of TPOAb. A total of 318 euthyroid female twin individuals distributed in 159 pairs were investigated. XCI was determined by PCR analysis of a polymorphic CAG repeat in the first exon of the androgen receptor gene. TPOAb concentrations were measured using a solid-phase time-resolved fluoroimmunometric assay. Overall (within cohort), there was a significant association between XCI and serum concentrations of TPOAb; regression coefficient (β)=1.45 (95% confidence interval, 0.52–2.38), P=0.003. The association remained significant in the within-pair analysis; β=1.74 (0.79–2.69), P<0.001. The relationship was nonsignificant within the 82 monozygotic pairs (β=0.57 (−0.78–1.92), P=0.405), whereas the association was significant in the 77 dizygotic pairs (β=2.17 (0.81–3.53), P=0.002). This preliminary finding of a significant association between TPOAb concentrations and XCI within cohort and within dizygotic but not within monozygotic twin pairs may indicate that XCI per se does not have a major role in the pathogenesis of TPOAb. More likely, XCI and TPOAb are influenced by shared genetic determinants.
X-chromosome inactivation; thyroid peroxidase antibodies; thyroid autoantibodies; thyroid autoimmunity; twins; epigenetics
The majority of autoimmune diseases such as rheumatoid arthritis (RA) and autoimmune thyroid diseases (AITDs) are characterized by a striking female predominance superimposed on a predisposing genetic background. The role of extremely skewed X-chromosome inactivation (XCI) has been questioned in the pathogenesis of several autoimmune diseases.
We examined XCI profiles of females affected with RA (n = 106), AITDs (n = 145) and age-matched healthy women (n = 257). XCI analysis was performed by enzymatic digestion of DNA with a methylation sensitive enzyme (HpaII) followed by PCR of a polymorphic CAG repeat in the androgen receptor (AR) gene. The XCI pattern was classified as skewed when 80% or more of the cells preferentially inactivated the same X-chromosome.
Skewed XCI was observed in 26 of the 76 informative RA patients (34.2%), 26 of the 100 informative AITDs patients (26%), and 19 of the 170 informative controls (11.2%) (P < 0.0001; P = 0.0015, respectively). More importantly, extremely skewed XCI, defined as > 90% inactivation of one allele, was present in 17 RA patients (22.4%), 14 AITDs patients (14.0%), and in only seven controls (4.1%, P < 0.0001; P = 0.0034, respectively). Stratifying RA patients according to laboratory profiles (rheumatoid factor and anti-citrullinated protein antibodies), clinical manifestations (erosive disease and nodules) and the presence of others autoimmune diseases did not reveal any statistical significance (P > 0.05).
These results suggest a possible role for XCI mosaicism in the pathogenesis of RA and AITDs and may in part explain the female preponderance of these diseases.
Objective: Androgen receptor (AR) was detected in leiomyoma. AR gene has a polymorphic microsatellite encoding cytosine, adenine, and guanine (CAG) repeats. We aimed to investigate the association between the AR gene CAG repeats and leiomyoma.
Methods: Women were divided into two groups: (1) leiomyoma (n=159); (2) non- leiomyoma groups (n=129). Their CAG repeats were detected by polymerase chain reaction. The CAG repeats ranged in length from 168 bp (9 CAG repeats, genotype A) to 234 bp (31 CAG repeats, genotype W). Distributions of CAG repeats in both groups were compared.
Results: Genotype proportions of different CAG repeats for AR gene in both groups were significantly different. The genotype S (27 CAG repeats) is associated with higher susceptibility of leiomyoma. Distribution of CAG repeats in both groups appeared mono-peak distributions. Percentages of genotypes K-S (19–27 CAG repeats) in leiomyoma and non-leiomyoma groups were: (1) 5, 11, 19.5, 10.4, 12.9, 8.8, 7.5, 5.7, 4.4%; (2) 5.4, 14.3, 16.7, 12.8, 12.4, 5.8, 9.3, 7, 1.2%.
Conclusions: AR trinucleotide polymorphism is associated with leiomyoma susceptibility. The 27 CAG repeats is related with higher risk of leiomyoma.
Androgen receptor; leiomyoma; multiallele polymorphism; trinucleotide repeat polymorphism
All female mammals with two X chromosomes balance gene expression with males having only one X by inactivating one of their Xs (X chromosome inactivation, XCI). Analysis of XCI in females offers the opportunity to investigate both X-linked genetic factors and early embryonic development that may contribute to alcoholism. Increases in the prevalence of skewing of XCI in women with alcoholism could implicate biological risk factors.
The pattern of XCI was examined in DNA isolated in blood from 44 adult females meeting DSM IV criteria for an Alcohol Use Disorder, and 45 control females with no known history of alcohol abuse or dependence. XCI status was determined by analyzing digested and undigested polymerase chain reaction (PCR) products of the polymorphic androgen receptor (AR) gene located on the X chromosome. Subjects were categorized into 3 groups based upon the degree of XCI skewness: random (50:50–64:36), moderately skewed (65:35–80:20) and highly skewed (>80:20).
XCI status from informative females with alcoholism was found to be random in 59% (n=26), moderately skewed in 27% (n=12) or highly skewed in 14% (n=6). Control subjects showed 60%, 29% and 11%, respectively. The distribution of skewed XCI observed among women with alcoholism did not differ statistically from that of control subjects (χ2 =0.14, 2 df, p=0.93).
Our data did not support an increase in XCI skewness among women with alcoholism or implicate early developmental events associated with embryonic cell loss or unequal (non-random) expression of X-linked gene(s) or defects in alcoholism among females.
Alcoholism; Women; X Chromosome Inactivation; Skewness; AR Gene
Prostate cancer (PC) is the second leading cause of cancer deaths in men. The effects of androgens on prostatic tissue are mediated by the androgen receptor (AR) gene. The 5′ end of exon 1 of the AR gene includes a polymorphic CAG triplet repeat that numbers between 10 to 36 in the normal population. The length of the CAG repeats is inversely related to the transactivation function of the AR gene. There is controversy over association between short CAG repeat numbers in the AR gene and PC. This retrospective case-control study evaluates the possible effect of short CAG repeats on the AR gene in prostate cancer risk in Macedonian males. A total of 392 male subjects, 134 PC patients, 106 patients with benign prostatic hyperplasia (BPH) and 152 males from the general Macedonian population were enrolled in this study. The CAG repeat length was determined by fluorescent polymerase chain reaction (PCR) amplification of exon1 of the AR gene followed by capillary electrophoresis (CE) on a genetic analyzer. The mean repeat length in PC patients was 21.5 ± 2.65, in controls 22.28 ± 2.86 (p = 0.009) and in BPH patients 22.1 ± 2.52 (p = 0.038). Short CAG repeats (<19) were found in 21.64% of PC patients vs. 9.43% in BPH patients (p = 0.0154). We also found an association of low Gleason score (<7) with short CAG repeat (<19) in PC patients (p = 0.0306), and no association between the age at diagnosis of PC and BPH and CAG repeat length. These results suggest that reduced CAG repeat length may be associated with increased prostate cancer risk in Macedonian men.
Prostrate cancer (PC); Androgen receptor (AR) gene; CAG repeat; Benign prostatic hyperplasia (BPH)
We attempt to ascertain if the 3 linked single nucleotide polymorphisms (SNPs) of the Progesterone Receptor (PR) gene (exon 1: G 1031 C; S344T, exon 4: G 1978 T; L660V and exon 5: C 2310 T; H770H) and the PROGINS insertion in the intron G, between exons 7 and 8, are associated with Recurrent Spontaneous Abortion (RSA) in the Indian population.
A total of 143 women with RSA and 150 controls were sequenced for all the 8 exons looking for the above 3 linked SNPs of the PR gene earlier implicated in the RSA, as well as for any new SNPs that may be possibly found in the Indian population. PROGINS insertion was screened by electrophoresis. We did not find any new mutations, not observed earlier, in our population. Further, we did not find significant role of the *2 allele (representing the mutant allele at the three SNP loci) or the T2 allele (PROGINS insertion) in the manifestation of RSA. We also did not find an LD pattern between each of the 3 SNPs and the PROGINS insertion.
The results suggest that the PR gene mutations may not play any exclusive role in the manifestation of RSA, and instead, given significantly higher frequency of the *2 allele among the normal women, we surmise if it does not really confer a protective role among the Indian populations, albeit further studies are required in the heterogeneous populations of this region before making any conclusive statement.
The length of the polymorphic CAG repeat in the N-terminal of the androgen receptor (AR) gene is inversely correlated with the transactivation function of the AR. Some studies have indicated that short CAG repeats are related to higher risk of prostate cancer. We performed a case–control study to investigate relations between CAG repeat length and prostate cancer risk, tumour grade, tumour stage, age at diagnosis and response to endocrine therapy. The study included 190 AR alleles from prostate cancer patients and 186 AR alleles from female control subjects. All were whites from southern Sweden. The frequency distribution of CAG repeat length was strikingly similar for cases and controls, and no significant correlation between CAG repeat length and prostate cancer risk was detected. However, for men with non-hereditary prostate cancer (n = 160), shorter CAG repeats correlated with younger age at diagnosis (P = 0.03). There were also trends toward associations between short CAG repeats and high grade (P = 0.07) and high stage (P = 0.07) disease. Furthermore, we found that patients with long CAG repeats responded better to endocrine therapy, even after adjusting for pretreatment level of prostate-specific antigen and tumour grade and stage (P = 0.05). We conclude that short CAG repeats in the AR gene correlate with young age at diagnosis of prostate cancer, but not with higher risk of the disease. Selection of patients with early onset prostate cancer in case–control studies could therefore lead to an over-estimation of the risk of prostate cancer for men with short CAG repeats. An association between long CAG repeats and good response to endocrine therapy was also found, but the mechanism and clinical relevance are unclear. © 1999 Cancer Research Campaign
prostatic neoplasms; cancer risk; androgen receptor; genetics; epidemiology
To investigate associations between the androgen receptor (AR) polymorphisms as CAG repeats, GGC repeats and c.211G>A polymorphism and the risk of preeclampsia.
The AR polymorphisms were experienced in 184 preeclamptic patients and 190 normal pregnancies and analyzed by multiple logistic regression.
Women with GGC repeats>16 were more frequently observed in preeclampsia, compared to those with GGC repeats≤16 [adjOR (95% CI): 3.64 (1.71–6.23)]. However, no significant differences were observed between the two groups with respect to CAG repeats. The genotypic and allelic frequencies of c.211G>A variant were significantly higher in cases than in controls (P < 0.05 for both). In the combined distribution of these polymorphisms, the highest risk of preeclampsia was found among women with the haplotype as CAG > 20/GA/GGC>16 [adjOR (95% CI): 4.26 (1.92–12.23)].
Our findings suggest that longer GGC repeats and c.211G>A variant in the AR gene are associated with increased susceptibility to the risk of preeclampsia.
Androgen receptor; CAG repeats; GGC repeats; c.211G>A polymorphism; Preeclampsia
Recurrent spontaneous abortion (RSA) defines as two or more consecutive losses at ≤20 weeks of gestation and affects an estimated 1 of every 100 couples wishing to have children. However, it remains a poorly understood phenomenon. Recent reports observed a significant association between highly skewed X chromosome and RSA, supporting that X chromosome inactivation might be an important and previously unknown cause of RSA. X-inactivation pattern, using polymeric X-linked women with idiopathic RSA and 80 control subjects with a single successful pregnancy and no history of spontaneous abortion. The ratio of heterozygotes was 68.2% (45/66) in women with RSA and 67.5% (54/80) in control group. Among 45 informative RSA cases, only 1 (2.2%) woman showed extreme skewed X inactivation (≥90%) and 4 (8.9%) had mild skewed inactivation (≥85%). In 54 heterozygous control subjects, 5 (9.3%) women showed extreme skewed X inactivation and 7 (13.0%) had mild one. The frequency of skewed X inactivation between RSA patients and control group was not significantly different (p>0.05). This finding suggests that skewed X chromosome be not associated with unexplained RSA patients.
Abortion, Spontaneous; X chromosome; Receptors, Androgen
Anogenital distance (AGD) is used to define degree of virilization of genital development, with shorter length being associated with feminization and male infertility. The first exon of the androgen receptor (AR) consists of a polymorphic sequence of cytosine–adenine–guanine (CAG) repeats, with longer CAG repeat lengths being associated with decreased receptor function. We sought to determine if there is an association between AGD and AR CAG repeat length. A cross-sectional, prospective cohort of men evaluated at a urology clinic at a single institution was recruited. AGD (the distance from the posterior scrotum to the anal verge) and penile length (PL) were measured. Sanger DNA sequence analysis was used to define CAG repeat length. AGD and CAG repeat lengths in 195 men were determined. On unadjusted analysis, there was no linear relationship between CAG repeat length and PL (P=0.17) or AGD (P=0.31). However, on sub-population analyses, those men with longer CAG repeat lengths (>26) had significantly shorter AGDs compared to men with shorter CAG repeat lengths. For example, the mean AGD was 41.9 vs. 32.4 mm with a CAG repeat length ≤26 vs. >26 (P=0.01). In addition, when stratifying the cohort based on AGD, those with AGD less than the median (i.e. 40 mm) had a longer CAG repeat length compared to men with an AGD >40 mm (P=0.02). In summary, no linear relationship was found between AGD and AR CAG repeat length overall.
androgen receptor (AR); anogenital distance (AGD); genitalia; penile length (PL); perineum
The aim of this study was to examine whether CAG/GGN repeats are significant modulators of serum concentrations of total and free testosterone (T) as well as of luteinizing hormone (LH) in elderly men. Sixty-nine 60- to 80-year-old men with subnormal T levels (≤ 11.0 nmol L−1) and 104 men with normal T levels taking part in a nested case-control study were used for these analyses. Sex hormones were measured and free T was calculated. The CAG and GGN polymorphisms in the androgen receptor gene were determined by polymerase chain reaction and subsequent direct sequencing. There were no differences in the CAG and GGN repeat lengths between the groups. In cross-sectional analyses of the whole cohort, total and free T were positively associated with CAG length (all P < 0.05) before, but not after, waist circumference or body mass index was added to the model. CAG repeat lengths were weakly, but not independently, associated with total and free T. These findings indicate that when clinically evaluating T and LH levels in elderly men, the CAG and GGN repeat lengths do not need to be taken into consideration.
androgen receptor gene polymorphism; luteinizing hormone; testosterone
To determine whether androgen receptor (AR) CAG (polyglutamine) and GGN (polyglycine) polymorphisms influence bone mineral density (BMD), osteocalcin and free serum testosterone concentration in young men.
Whole body, lumbar spine and femoral bone mineral content (BMC) and BMD, Dual X-ray Absorptiometry (DXA), AR repeat polymorphisms (PCR), osteocalcin and free testosterone (ELISA) were determined in 282 healthy men (28.6±7.6 years). Individuals were grouped as CAG short (CAGS) if harboring repeat lengths of ≤21 or CAG long (CAGL) if CAG >21, and GGN was considered short (GGNS) or long (GGNL) if GGN ≤23 or >23. There was an inverse association between logarithm of CAG and GGN length and Ward's Triangle BMC (r = −0.15 and −0.15, P<0.05, age and height adjusted). No associations between CAG or GGN repeat length and regional BMC or BMD were observed after adjusting for age. Whole body and regional BMC and BMD values were similar in men harboring CAGS, CAGL, GGNS or GGNL AR repeat polymorphisms. Men harboring the combination CAGL+GGNL had 6.3 and 4.4% higher lumbar spine BMC and BMD than men with the haplotype CAGS+GGNS (both P<0.05). Femoral neck BMD was 4.8% higher in the CAGS+GGNS compared with the CAGL+GGNS men (P<0.05). CAGS, CAGL, GGNS, GGNL men had similar osteocalcin concentration as well as the four CAG-GGN haplotypes studied.
AR polymorphisms have an influence on BMC and BMD in healthy adult humans, which cannot be explained through effects in osteoblastic activity.
Considerably little is known about the biological role and clinical significance of androgen receptor expression in breast cancer. The objectives of this study were to characterize AR-CAG repeat genotypes in a cohort of women with breast cancer and to determine the influence of AR on response to neoadjuvant chemotherapy and clinical outcome.
Materials and methods
Genotyping of the AR CAG repeat region was done on 70 patients and 80 healthy aged- matched female controls. To assess response to NACT, tissue samples from 30 LABC cases were evaluated quantitatively by real time for AR mRNA expression. The clinical response was correlated with both the pre and post chemotherapy AR expression. The CAG alleles did not show differences between cases and controls when the mean of short, long and average length of both CAG alleles was considered. However, analysis when done defining short allele as CAGn < 20 (AR1) and the long as CAGn ≥ 20 (AR2), risk was found associated with AR2 allele with marginal significance (P = 0.09). Stratification by age of onset, FH, stage, grade ER and AR status failed to reveal any association with breast cancer risk. Genotype carriers with ≥20 CAGn showed decrease of AR mRNA expression although significance could not be established (P = 0.47). Tumours in responders had the higher AR mRNA expression levels in pre neo-adjuvant chemotherapy condition (p < 0.02) which got reduced after neoadjuvant chemotherapy and the difference was found to be significant (P = 0.014).
Although, expansion of the CAGn in the AR gene doesn't show any major effect on breast cancer risk, patients with positive AR expression, pre neoadjuvant chemotherapy, were found to be good responders and a decrease in mRNA level of AR gene related to the chemotherapy-induced apoptosis could serve as an important independent predictor of response to NACT.
Rejection of semiallogenic foetus in recurrent spontaneous abortion (RSA) has been postulated to be a consequence of genetic and immunological phenomena.
To evaluate the role of human leukocyte antigen (HLA) alleles in RSA in Indian couples.
SETTINGS AND DESIGN:
A case-control study.
MATERIALS AND METHODS:
Eighty-one randomly selected couples with unexplained three or more RSAs and a control group of 97 couples with live birth belonging to the same ethnic background, referred to the Gynaecology Department, KEM Hospital were included in the case-control study. Serological HLA A and B typing was done followed by molecular subtypes, defined using PCR-SSOP technique for HLA A, B, and C in 40 couples and DRB1* and DQB1* in 28 couples which were then compared with appropriate case 46 and 88 controls.
Serologically A3 (15.43% vs. 4.43%; odds ratio (OR) = 4.34; P = 0.0002) and B17 (25.3% vs. 11.34%; OR = 3.49; P = 0.0001) were increased. Haplotype A1-B17 was significantly increased. Molecular subtyping revealed that A*030102 (11.25% vs. 4.34%; OR = 3.00; P = 0.07), B*5701 (11.25% vs. 1.08%; OR = 13.10; P = 0.003), Cw*120201 (25% vs. 4.34%; OR = 10.50; P = 2.05E-05), HLA DRB1*030101 (17.85% vs. 3.40%; OR = 7.6; P = 0.0001), DRB1*150101 (32.14% vs. 13.63%; OR = 4.8; P = 0.0003), and DQB1*060101 (35.71% vs. 29.34%; OR = 2.3; P = 0.004) were significantly increased in patients. A differential association was noticed when compared with reported world RSA patients.
The HLA alleles A*030101, B*5701, Cw*120201, DRB1*030101, and DRB1*150101 as well as their associated ancestral haplotype may play a significant role in development of RSA in India.
Cw*120201; DQB1*050301 association; HLA B*5701; India; RSA
Increasing rates of testicular germ cells tumors (TGCTs) overtime suggest that environmental factors are involved in disease etiology, but familial risk and genome-wide association studies implicate genetic factors as well. We investigated whether variation in the functional CAGn polymorphism in the androgen receptor (AR) gene is associated with TGCT risk, using data from a population-based family study. We estimated odds ratios (OR) and 95% confidence intervals (CI) for the association of CAG repeat length and TGCT risk using matched pairs logistic regression. Analyses of 273 TGCT case–mother pairs revealed no association between AR CAG repeat length and overall TGCT risk. However, risk of seminoma was significantly associated with shorter CAG repeat length [CAG 20–21 versus CAG ≤ 19: OR = 0.82 (95% CI: 0.43–1.58), CAG 22–23 versus CAG ≤ 19: OR = 0.39 (95% CI: 0.19–0.83) and CAG ≥ 24 versus CAG ≤ 19: OR = 0.42 (95% CI: 0.20–0.86)], with a highly significant trend over these four categories of decreasing CAG repeat length (Ptrend = 0.0030). This is the first report of a statistically significant association between AR CAG repeat length and seminoma risk, suggesting that increased AR transactivation may be involved in development of seminoma and/or progression of carcinoma in situ/intratubular germ cell neoplasia unclassified to seminoma. This result provides a rationale whereby androgenic environmental compounds could contribute to increases in TGCT incidence, and identifies for the first time a potential biological pathway influencing whether TGCTs achieve seminomatous versus nonseminomatous histology, a clinically and biologically important distinction.
The androgen receptor (AR) expression and the CAG repeat length within the AR gene appear to be involved in the carcinogenesis of male breast carcinoma (MBC). Although phenotypic differences have been observed between MBC and normal control group in AR gene, there is lack of correlation analysis between AR expression and CAG repeat length in MBC. The purpose of the study was to investigate the prognostic value of CAG repeat lengths and AR protein expression.
81 tumor tissues were used for immunostaining for AR expression and CAG repeat length determination and 80 normal controls were analyzed with CAG repeat length in AR gene. The CAG repeat length and AR expression were analyzed in relation to clinicopathological factors and prognostic indicators.
AR gene in many MBCs has long CAG repeat sequence compared with that in control group (P = 0.001) and controls are more likely to exhibit short CAG repeat sequence than MBCs. There was statistically significant difference in long CAG repeat sequence between AR status for MBC patients (P = 0.004). The presence of long CAG repeat sequence and AR-positive expression were associated with shorter survival of MBC patients (CAG repeat: P = 0.050 for 5y-OS; P = 0.035 for 5y-DFS AR status: P = 0.048 for 5y-OS; P = 0.029 for 5y-DFS, respectively).
The CAG repeat length within the AR gene might be one useful molecular biomarker to identify males at increased risk of breast cancer development. The presence of long CAG repeat sequence and AR protein expression were in relation to survival of MBC patients. The CAG repeat length and AR expression were two independent prognostic indicators in MBC patients.
Genetic variation in the androgen receptor gene (AR) may be associated with endometrial cancer risk based on the androgen receptor’s role in regulating androgen levels. However, endometrial cancer studies reported inconsistent associations for a CAG repeat polymorphism in exon 1. Only one of these studies measured haplotype-tagging single nucleotide polymorphisms (htSNPs) in AR, and found statistically non-significant, decreased associations with endometrial cancer risk. In a population-based case-control study of 497 cases and 1024 controls, we examined the CAG repeat polymorphism and six htSNPs (rs962458, rs6152, rs1204038, rs2361634, rs1337080, and rs1337082), which cover an estimated 80% of the known common variation in AR among Caucasian populations. CAG repeat length was not significantly associated with endometrial cancer (OR (95%CI) per unit increase in the average number of repeats =1.02 (0.97 – 1.08); P-trend=0.29). Minor alleles in three correlated htSNPs (rs6152, rs1204038, and rs1337082; r2≥0.6) were associated with increased risk for endometrial cancer. The strongest association was observed for rs6152: the ORs (95% CIs) were 1.13 (0.89–1.44) for heterozygous and 2.40 (1.28–4.51) for homozygous minor genotypes (P-trend=0.02), compared to homozygous major allele genotype. However, these associations were not statistically significant after permutation adjustment for multiple comparisons (P-trend ≥ 0.09). Haplotype analyses did not reveal any additional associations with endometrial cancer. Results from our study taken together with previously published studies provide little evidence of a consistent association between common genetic variation in AR and endometrial cancer risk.
genetics; endometrial cancer; androgen receptor
Polycystic ovarian syndrome (PCOS) refers to an inheritable androgen excess disorder characterized by multiple small follicles located at the ovarian periphery. Hyperandrogenism in PCOS, and inverse correlation between androgen receptor (AR) CAG numbers and AR function, led us to hypothesize that CAG length variations may affect PCOS risk.
CAG repeat region of 169 patients recruited following strictly defined Rotterdam (2003) inclusion criteria and that of 175 ethnically similar control samples, were analyzed. We also conducted a meta-analysis on the data taken from published studies, to generate a pooled estimate on 2194 cases and 2242 controls.
CAG bi-allelic mean length was between 8.5 and 24.5 (mean = 17.43, SD = 2.43) repeats in the controls and between 11 and 24 (mean = 17.39, SD = 2.29) repeats in the cases, without any significant difference between the two groups. Further, comparison of bi-allelic mean and its frequency distribution in three categories (short, moderate and long alleles) did not show any significant difference between controls and various case subgroups. Frequency distribution of bi-allelic mean in two categories (extreme and moderate alleles) showed over-representation of extreme sized alleles in the cases with marginally significant value (50.3% vs. 61.5%, χ2 = 4.41; P = 0.036), which turned insignificant upon applying Bonferroni correction for multiple comparisons. X-chromosome inactivation analysis showed no significant difference in the inactivation pattern of CAG alleles or in the comparison of weighed bi-allelic mean between cases and controls. Meta-analysis also showed no significant correlation between CAG length and PCOS risk, except a minor over-representation of short CAG alleles in the cases.
CAG bi-allelic mean length did not differ between controls and cases/case sub-groups nor did the allele distribution. Over-representation of short/extreme-sized alleles in the cases may be a chance finding without any true association with PCOS risk.
Purpose: To investigate the relationship between CAG repeat length in the androgen receptor gene and impaired spermatogenesis in Hong Kong Chinese population.
Methods: The CAG repeat region was amplified by polymerase chain reaction (PCR) in 85 nonobstructive azoospermic or severe oligozoospermic men, and 45 fertile males. The number of CAG repeat was analyzed by DNA sequencing. Serum FSH, LH, and testosterone levels were also determined in these men.
Results: Among nonobstructive azoospermic males, three men (5.7%) possessed short CAG repeats (<16), and three (5.7%) other men possessed long CAG repeats (>30). Short CAG repeats (<16) were also found in two severe oligozoospermic males (6.3%). The incidence of infertile men with short or long CAG repeats is significantly higher in the azoospermic group (p = 0.03) but not in the severe oligozoospermic group (p = 0.17) when compared with the fertile controls.
Conclusion: Our data suggest an association between CAG repeat lengths and impaired spermatogenesis in azoospermic males in our population.
Androgen receptor; CAG repeat; male infertility
The androgen receptor (AR) gene exon 1 CAG repeat polymorphism encodes a string of 9–32 glutamines. Women with germline BRCA1 mutations who carry at least one AR allele with 28 or more repeats have been reported to have an earlier age at onset of breast cancer.
A total of 604 living female Australian and British BRCA1 and/or BRCA2 mutation carriers from 376 families were genotyped for the AR CAG repeat polymorphism. The association between AR genotype and disease risk was assessed using Cox regression. AR genotype was analyzed as a dichotomous covariate using cut-points previously reported to be associated with increased risk among BRCA1 mutation carriers, and as a continuous variable considering smaller allele, larger allele and average allele size.
There was no evidence that the AR CAG repeat polymorphism modified disease risk in the 376 BRCA1 or 219 BRCA2 mutation carriers screened successfully. The rate ratio associated with possession of at least one allele with 28 or more CAG repeats was 0.74 (95% confidence interval 0.42–1.29; P = 0.3) for BRCA1 carriers, and 1.12 (95% confidence interval 0.55–2.25; P = 0.8) for BRCA2 carriers.
The AR exon 1 CAG repeat polymorphism does not appear to have an effect on breast cancer risk in BRCA1 or BRCA2 mutation carriers.
AR; BRCA1; BRCA2; modifier
Leflunomide (LEF) is a disease-modifying antirheumatic drug used for treating rheumatoid arthritis (RA) and the action of which may be modified by sex hormones. The aim of this study was to examine the association between CAG repeat polymorphism in the androgen receptor (AR) gene and the response to treatment with LEF in women with RA.
We studied 114 women diagnosed with RA and treated with LEF (20 mg daily). Follow-up was 12 months. CAG repeat polymorphism was determined using polymerase chain reaction (PCR) and subsequent fragment analysis by capillary electrophoresis.
Analysis revealed no statistically significant associations between CAG repeat polymorphism in the AR gene and improvement of disease activity parameters: erythrocyte sedimentation rate, serum C-reactive protein, patient’s global assessment of disease activity on a visual analog scale (VAS), disease activity score of 28 joints (DAS28), and swollen and tender joint count.
Our results suggest no correlation between CAG repeat polymorphism in the AR gene and response to treatment with LEF in women with RA.
(CAG)n repeat polymorphism; Androgen receptor; Leflunomide; Rheumatoid arthritis
Adamantinoma is a low-grade, malignant biphasic bone tumour predominantly located in the tibia. In up to 50% of all cases this is combined with one or more lesions in the ipsilateral fibula. Whether these lesions represent regional metastases or arise de novo is not yet exactly known. In order to address this question, we extracted DNA from the respective fresh frozen tumour tissues in a case of a young woman with a multifocal adamantinoma of both the tibia and ipsilateral fibula. Afterwards the X inactivation pattern was studied by means of methylation-sensitive polymerase chain reaction and primers that target the polymorphic CGG trinucleotide repeat of FMR1 gene and the polymorphic CAG repeat, on exon 1 of the human androgen receptor gene (AR). The analysis of the AR was homozygous and not informative. Studying the FMR1 gene, we detected a 100% skewing of the X inactivation pattern of both locations and found that the same allele was methylated. Even if the fibula lesion arose de novo there would have been a 50 : 50 chance that the same allele was methylated. As this methylation pattern was found we cannot provide a valid explanation for the origin of the fibula lesion. Analysis of X inactivation patterns in future cases of polyfocal adamantinoma might provide further evidence for one of the two theories.
Scleroderma is a female-prevalent autoimmune disease of unclear etiology. Two fundamental gender differences, skewed X-chromosome inactivation (XCI) and pregnancy-related microchimerism have been implicated in scleroderma. We investigated the XCI patterns of female scleroderma patients and the parental origin of the inactive X chromosome in those patients having skewed XCI patterns (>80%). In addition, we investigated whether a correlation exists between XCI patterns and microchimerism in a well-characterized cohort. 195 female scleroderma patients and 160 female controls were analyzed for the androgen receptor locus to assess XCI patterns in the DNA extracted from peripheral blood cells. Skewed XCI was observed in 67 (44.9%) of 149 informative patients and in 10 of 124 healthy controls (8.0%) [odds ratio (OR) = 9.3 (95% confidence interval (CI) 4.3-20.6, P<0.0001)]. Extremely skewed XCI (>90%) was present in 44 of 149 patients (29.5%) but only in 3 of 124 controls (2.4%) (OR=16.9; 95% CI 4.8-70.4, P<0.0001). Parental origin of the inactive X chromosome was investigated for 10 patients for whom maternal DNA was informative, and the inactive X chromosome was of maternal origin in 8 patients and of paternal origin in 2 patients. Skewed XCI mosaicism could be considered as an important risk factor in scleroderma.
X-inactivation; microchimerism; mosaicism; scleroderma
Variation in the penetrance estimates for BRCA1 and BRCA2 mutations carriers suggests that other genetic polymorphisms may modify the cancer risk in carriers. A previous study has suggested that BRCA1 carriers with longer lengths of the CAG repeat in the androgen receptor (AR) gene are at increased risk of breast cancer (BC). We genotyped 188 BRCA1/2 carriers (122 affected and 66 unaffected with breast cancer), 158 of them of Ashkenazi origin, 166 BC cases without BRCA1/2 mutations and 156 Ashkenazi control individuals aged over 56 for the AR CAG and GGC repeats. In carriers, risk analyses were conducted using a variant of the log-rank test, assuming two sets of risk estimates in carriers: penetrance estimates based on the Breast Cancer Linkage Consortium (BCLC) studies of multiple case families, and lower estimates as suggested by population-based studies. We found no association of the CAG and GGC repeats with BC risk in either BRCA1/2 carriers or in the general population. Assuming BRCA1/2 penetrance estimates appropriate to the Ashkenazi population, the estimated RR per repeat adjusted for ethnic group (Ashkenazi and non-Ashkenazi) was 1.05 (95%CI 0.97–1.17) for BC and 1.00 (95%CI 0.83–1.20) for ovarian cancer (OC) for CAG repeats and 0.96 (95%CI 0.80–1.15) and 0.90 (95%CI 0.60–1.22) respectively for GGC repeats. The corresponding RR estimates for the unselected case–control series were 1.00 (95%CI 0.91–1.10) for the CAG and 1.05 (95%CI 0.90–1.22) for the GGC repeats. The estimated relative risk of BC in carriers associated with ≥28 CAG repeats was 1.08 (95%CI 0.45–2.61). Furthermore, no significant association was found if attention was restricted to the Ashkenazi carriers, or only to BRCA1 or BRCA2 carriers. We conclude that, in contrast to previous observations, if there is any effect of the AR repeat length on BRCA1 penetrance, it is likely to be weak. © 2001 Cancer Research Campaign http://www.bjcancer.com
BRCA1/2; androgen receptor; polymorphisms; breast cancer risk