Yvonne Lundberg Giwercman

A genome-wide association study of men with symptoms of testicular dysgenesis syndrome and its network biology interpretation

Background Testicular dysgenesis syndrome (TDS) is a common disease that links testicular germ cell cancer, cryptorchidism and some cases of hypospadias and male infertility with impaired development of the testis. The incidence of these disorders has increased over the last few decades, and testicular cancer now affects 1% of the Danish and Norwegian male population. Methods To identify genetic variants that span the four TDS phenotypes, the authors performed a genome-wide association study (GWAS) using Affymetrix Human SNP Array 6.0 to screen 488 patients with symptoms of TDS and 439 selected controls with excellent reproductive health. Furthermore, they developed a novel integrative method that combines GWAS data with other TDS-relevant data types and identified additional TDS markers. The most significant findings were replicated in an independent cohort of 671 Nordic men. Results Markers located in the region of TGFBR3 and BMP7 showed association with all TDS phenotypes in both the discovery and replication cohorts. An immunohistochemistry investigation confirmed the presence of transforming growth factor β receptor type III (TGFBR3) in peritubular and Leydig cells, in both fetal and adult testis. Single-nucleotide polymorphisms in the KITLG gene showed significant associations, but only with testicular cancer. Conclusions The association of single-nucleotide polymorphisms in the TGFBR3 and BMP7 genes, which belong to the transforming growth factor β signalling pathway, suggests a role for this pathway in the pathogenesis of TDS. Integrating data from multiple layers can highlight findings in GWAS that are biologically relevant despite having border significance at currently accepted statistical levels.

Functional in vitro characterisation of the androgen receptor GGN polymorphism.

Superior androgen receptor (AR) function in subjects carrying a GGN repeat length of 23 (GGN23) has been indicated in vivo. Therefore, the activity of the AR carrying GGN23 combined with CAG22 was compared to the AR with GGN10, 24 and 27, respectively, in the presence of 0.1-100 nM testosterone or DHT. At 100 nM DHT, GGN24 showed 35% lower transactivating activity (95% [CI]: 20-50%) than GGN23. GGN10 and GGN27 also showed significantly less AR activity than GGN23 (mean differences [95% CI]: 54% [40-68%] and 58% [39-78%], respectively). The same trend was also observed at lower DHT concentrations. In response to R1881, GGN23 activity was significantly higher than for other lengths. ARs with other glutamine numbers than 23 have lower transactivating capacity in response to both testosterone and DHT. Congenital malformations and other signs of hypoandrogenism in subjects with AR gene GGN lengths other than 23 could, hence, be related to a lower AR activity.

CAG repeat number is not inversely associated with androgen receptor activity in vitro.

A negative linear association between androgen receptor (AR) function and the CAG repeat numbers is generally assumed. However, in vivo data concerning the association between CAG number and androgenic effects have been conflicting. Since former in vitro studies mostly have been based on extreme CAG lengths and reporter-systems containing viral promoters, the objective of this study was to investigate ARs with CAG lengths within normal range (16, 22 and 28) in a reporter-assay with the human prostate specific antigen promoter as target. We also wished to elucidate whether the interpretation of the results was depending on the methods used for adjustment of transfection efficiency and protein content. With beta-galactosidase as transfection control, 22CAG had the highest activity (set to 100%) compared with 16CAG [mean 78% (range 41-132), P = 0.005] and 28CAG [68% (26-162), P = 0.006], whereas renilla-luciferase resulted in 16CAG behaving similar to 22CAG [104% (56-165), P = 0.7] and 28CAG having lower activity [59% (33-101), P = 0.004]. In these experiments, also the empty vector displayed considerable background activity. When adjusting for AR protein, the 22CAG genotype had the highest activity; 16CAG and 28CAG displaying 20% (10-47, P < 0.0001) and 12% (5-21, P < 0.0001) thereof. Similar results were obtained with adjustment for total protein. Thus, by normalizing for AR-content, contrary to various control vectors, the highest AR activity was confined to the 22CAG and not 16 CAG, which may at least partly explain the discrepancy in data aiming to link physiological conditions to CAG repeat length.

Environmental factors and testicular function

Over the last decades there has been a dramatic increase in the incidence of some diseases associated with the male reproductive system, including poor semen quality, testicular cancer and congenital developmental abnormalities such as cryptorchidism and hypospadias, malformations of the urethra and scrotum respectively. Based on these observations one recurring theme is the concern that certain environmental chemicals and lifestyle related factors may play a role. Early fetal life is a particularly critical time period, when the endocrine system is established and organs are developing. Although available data does not yet allow recommending, evidence based, prophylactic and/or therapeutic measures to eliminate or reduce the possible negative impact of environment/lifestyle on the male reproductive capacity, it is prudent to limit exposures of people to hormonally active chemicals.

Negative Association between Testosterone Concentration and Inflammatory Markers in Young Men: A Nested Cross-Sectional Study

Objective Low grade systemic inflammation (LGSI) as well as androgen deficiency has in older men been associated with several pathologies, including cardiovascular disease (CVD). We wanted to investigate whether low testosterone levels are linked to biomarkers of LGSI already in young age, before any concurrent manifestations of CVD or other systemic diseases. Design Nested cross-sectional study. Methods Forty subfertile biochemically hypogonadal (n = 20) or eugonadal (n = 20) men (mean age 37 years, SD = 4.3) and 20 age-matched controls were randomly selected from an ongoing study on male subfertility. Subjects comprised male partners in infertile couples in whom also subnormal sperm concentration was present. Blood sampling, interviews, and anthropometric measures were undertaken. Serum levels of testosterone, LH, estradiol, SHBG, and 21 LGSI-markers were assessed. Results Among 21 inflammatory markers, macrophage inflammatory protein 1-alpha (MIP1a) (ß = −0.025; p = 0.028), 1-beta (MIP1B) (ß = −0.015; p = 0.049) and tumor necrosis factor alpha (TNFa) (ß = −0.015; p = 0.040) showed negative association to total testosterone (TT) levels. MIP1a (ß = −1.95; p = 0.001) and TNFa (ß = −0.95; p = 0.014) showed negative association to calculated free testosterone (cFT) levels. Compared to men with normal TT and cFT levels, TNFa levels were higher in men with subnormal levels of TT (mean ratio 1.61; p = 0.006) and cFT (mean ratio 1.58; p = 0.007). Also, MIP1a levels were higher in men with subnormal levels of TT (mean ratio 1.84; p = 0.030). Conclusions Subnormal testosterone may already in young age associate to LGSI, which might be a part of the mechanism underlying adverse health outcomes of male hypogonadism.

Hypogonadism Risk in Men Treated for Childhood Cancer.

CONTEXT Pediatric cancer treatment may imply an increased risk of hypogonadism, leading to metabolic disorders and osteoporosis. Such complications are potentially preventable. OBJECTIVE The aim of this study was to assess diagnosis- and treatment-dependent risk of hypogonadism in male childhood cancer survivors (CCS). DESIGN Male CCS who were treated during the period 1970-2002 and who in 2004 were 18-45 yr of age were eligible. SETTING The study was conducted in a university hospital clinic. PATIENTS A consecutive group of CCS treated at Lund University Hospital was selected for the study, of whom 151 (38%) agreed to participate. Furthermore, 141 healthy fertile men served as controls. INTERVENTIONS We measured serum levels of free and total testosterone, SHBG, and LH. MAIN OUTCOME MEASURES Odds ratios (OR) for biochemical hypogonadism, defined as total testosterone less than 10 nmol/liter and/or LH above 10 IU/liter, were calculated and related to type of cancer, treatment received, as well as testicular volume. RESULTS Hypogonadism was more commonly detected in CCS than in controls (OR, 6.7; 95% CI, 2.7, 17). The increased presence of hypogonadism was noted in the following treatment groups: brain surgery, chemotherapy (with and without radiotherapy), and testicular irradiation. Low total testicular volume (<or=24 ml) was associated with a high risk of hypogonadism (OR, 31; 95% CI, 11, 92). CONCLUSION Adult male survivors of childhood cancer are at risk of hypogonadism, which should be acknowledged in the long-term follow-up of these men.

Androgen receptor gene CAG repeat length as a modifier of the association between persistent organohalogen pollutant exposure markers and semen characteristics

Objectives Exposure to persistent organohalogen pollutants was suggested to impair male reproductive function. A gene–environment interaction has been proposed. No genes modifying the effect of persistent organohalogen pollutants on reproductive organs have yet been identified. We aimed to investigate whether the CAG and GGN polymorphisms in the androgen receptor gene modify the effect of persistent organohalogen pollutant exposure on human sperm characteristics. Methods Semen and blood from 680 men [mean (SD) age 34 (10) years] from Greenland, Sweden, Warsaw (Poland) and Kharkiv (Ukraine) were collected. Persistent organohalogen pollutant exposure was assessed by measuring serum levels of 2,2′,4,4′,5,5′-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p′-DDE). Semen characteristics (volume, sperm concentration, total count, proportion of progressively motile and morphology) and DNA fragmentation index (DFI) were determined. CAG and GGN repeat lengths were determined by direct sequencing of leukocyte DNA. Results A statistically significant interaction was found between the CB-153 group and CAG repeat category in relation to sperm concentration and total sperm count (P=0.03 and 0.01, respectively). For p,p′-DDE, in the European cohorts a significant interaction was found in relation to DFI (P=0.01). For CAG<20, sperm concentration and total sperm count were 35 and 42% lower, respectively, when the group with CB-153 exposure above median was compared with that below the median. DFI was 40% higher in the high p,p′-DDE exposure group for CAG≤21. Conclusions This study indicated that the androgen receptor CAG repeat length might modify the susceptibility of an individual to the adverse effects of persistent organohalogen pollutant exposure on semen quality. Other studies regarding this matter are warranted.

Impact of PCB and p,p'-DDE contaminants on human sperm Y:X chromosome ratio: studies in three European populations and the Inuit population in Greenland.

Objective Recent studies indicate that persistent organohalogen pollutants (POPs) may contribute to sex ratio changes in offspring of exposed populations. Our aim in the present study was to investigate whether exposure to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153) and dichlorodiphenyldichloroethene (p,p′-DDE) affects sperm Y:X chromosome distribution. Subjects and methods We obtained semen and blood for analysis of PCB-153 and p,p′-DDE levels from 547 men from Sweden, Greenland, Poland (Warsaw), and Ukraine (Kharkiv), with regionally different levels of POP exposure. The proportion of Y- and X-chromosome–bearing sperm in the semen samples was determined by two-color fluorescence in situ hybridization analysis. Results Swedish and Greenlandic men had on average significantly higher proportions of Y sperm (in both cohorts, 51.2%) and correspondingly higher lipid-adjusted concentrations of PCB-153 (260 ng/g and 350 ng/g, respectively) compared with men from Warsaw (50.3% and 22 ng/g) and Kharkiv (50.7% and 54 ng/g). In the Swedish cohort, log-transformed PCB-153 and log-transformed p,p′-DDE variables were significantly positively associated with Y-chromosome fractions (p-values 0.04 and < 0.001, respectively). On the contrary, in the Polish cohort PCB-153 correlated negatively with the proportion of Y-bearing fraction of spermatozoa (p = 0.008). Conclusions The present study indicates that POP exposure might be involved in changing the proportion of ejaculated Y-bearing spermatozoa in human populations. Intercountry differences, with different exposure situations and doses, may contribute to varying Y:X chromosome ratios.

Non-linear association between androgen receptor CAG-repeat length and risk of male subfertility - a meta-analysis

The CAG repeat in the androgen receptor (AR) has been widely studied in association with male infertility, but the results are conflicting. In a recent meta-analysis, infertile men had <1 repeat longer CAG stretch than fertile men when analysed in a linear regression model assuming that AR function diminishes with increasing CAG length. However, in vitro, a non-linear activity pattern was recently demonstrated so that ARs containing short and long stretches, respectively, displayed lower activity than the AR of median length. These results prompted us to explore the possible association between CAG number and male infertility risk in a stratified manner on the basis of data from the mentioned meta-analysis and subjects from our clinical unit. The study population included 3915 men, 1831 fertile and 2084 infertile. Data were divided into three categories: CAG<22, CAG 22-23 (reference) and CAG>23 and analysed in a binary logistic regression model. Men with CAG<22 and CAG>23 had 20% increased odds ratio of infertility compared with carriers of the median lengths [for CAG<22: p=0.03, 95% confidence interval (CI): 1.02-1.39; for CAG>23: p=0.02, 95% CI: 1.03-1.44]. These results show that an alternative model to a linear one for the genotype-phenotype association in relation to AR CAG repeats is likely, as lengths close to the median confine lowest risk of infertility.

Sexual Function in Men Treated for Testicular Cancer

INTRODUCTION Testicular germ cell cancer (TGCC) patients may be at risk of developing sexual dysfunction after treatment. AIM The aim of this study was to assess the prevalence of sexual dysfunctions in TGCC patients 3 to 5 years after treatment, and relate findings to biochemical hypogonadism, treatment intensity, and the expected prevalence in the Swedish male population. METHODS A questionnaire study on 129 consecutive TGCC patients 3 to 5 years post-treatment was performed. Comparators were an age-matched nationally representative group of men (N = 916) included in a study on sexual life in Sweden. MAIN OUTCOME MEASURES Sexual functions (including erectile dysfunctional distress), time since last intercourse, sexual satisfaction, and experience of sexological treatment seeking were assessed using the same questions used in the epidemiological study on sexual life in Sweden. The findings in TGCC patients were correlated to biochemical signs of hypogonadism and type of oncological treatment: Surveillance, adjuvant chemotherapy, adjuvant radiotherapy, or standard doses of chemotherapy. RESULTS A higher proportion of TGCC patients than comparators were likely to report low sexual desire (odds ratio [OR] 6.7 [95% confidence interval {CI} 2.1-21]) as well as erectile dysfunction (OR 3.8 [95% CI 1.4-10]). No significant differences were observed regarding erectile dysfunctional distress, change of desire over time, interest in sex, premature or delayed ejaculation, time since last intercourse, need for or receiving sexual advice, or sexual satisfaction. Hypogonadism did not predict erectile dysfunction (OR 1.1 [95% CI 0.26-4.5]) or low sexual desire (OR 1.2 [95% CI 0.11-14]). Treatment modality had no obvious impact on sexual function. CONCLUSION Men treated for testicular cancer had higher risk of having low sexual desire and erectile dysfunction 3 to 5 years after completion of therapy than comparators. These sexual dysfunctions were not significantly associated with treatment intensity or hypogonadism.