High risk of hypogonadism in young male cancer survivors

OBJECTIVE

Cancer and its treatment in childhood and young adulthood can cause hypogonadism, leading to increased risk of long-term morbidity and mortality. The aim of this study was to evaluate the risk of presenting with biochemical signs of hypogonadism in testicular cancer survivors (TCS) and male childhood cancer survivors (CCS) in relation to the type of treatment given.

DESIGN

Case-control study.

PATIENTS

Ninety-two TCS, 125 CCS (mean age 40 and median age 34 years, respectively; mean follow-up time 9.2 and 24 years, respectively) and a corresponding number of age-matched controls.

MEASUREMENTS

Fasting morning blood samples were analysed for total testosterone (TT), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The odds ratios (OR) for hypogonadism, defined as primary, secondary, compensated or ongoing androgen replacement, were calculated for TCS and CCS and for subgroups defined by diagnosis and treatment.

RESULTS

Hypogonadism was found in 26% of CCS and 36% of TCS, respectively (OR: 2.1, P = .025 and OR = 2.3, P = .021). Among CCS, the OR was further increased in those given testicular irradiation (OR = 28, P = .004). Radiotherapy other than cranial or testicular irradiation plus chemotherapy, or cranial irradiation without chemotherapy, associated also with increased ORs (OR = 3.7, P = .013, and OR = 4.4, P = .038, respectively). Among TCS, those receiving >4 cycles of cisplatin-based chemotherapy had OR = 17, P = .015.

CONCLUSIONS

Biochemical signs of testosterone deficiency are recognized as markers of decreased life expectancy. Thus, the risk of hypogonadism in TCS and CCS should be recognized and emphasizes the need of long-term follow-up for these men.

High prevalence of androgen deficiency and abnormal lipid profile in infertile men with non-obstructive azoospermia

In men with non-obstructive azoospermia (NOA), the risk of hypogonadism is often overlooked. Testicular sperm extraction (TESE) may increase this risk. The objective of this study was to elucidate the prevalence of hypogonadism in NOA-patients, the impact of TESE on hormone balance and the association between testosterone deficiency and dyslipidaemia. Men with NOA who had undergone TESE during the period 2004-2009 were eligible. Hypogonadism was defined as total testosterone <10 nmol/L and/or LH >10 IU/L and/or ongoing androgen replacement therapy. Sixty-five consecutive men who had undergone TESE owing to NOA and from whom post-TESE serum testosterone levels measured before 1100 h were available. Furthermore, 141 fertile men served as controls. Serum concentrations of testosterone, LH and lipids were assessed. Odds ratios (OR) for biochemical hypogonadism were calculated. Pre- and post-TESE hormone levels were compared. Lipid profile was related to testosterone levels. Hypogonadism was found in 47% (95% CI, 0.36, 0.59) of the NOA-men. As compared with fertile controls, the OR for hypogonadism post-TESE was 17 (95% CI 6.6-45). Serum LH (p = 0.03), but not testosterone (p = 0.43), differed significantly pre- and post-TESE. Compared with eugonadal NOA-men, the OR for having deviations in lipid profile was 3.3 (95% CI 1.3-8.8) for the hypogonadal NOA-men. NOA-men are at very high risk of androgen deficiency, which even in young subjects is associated with dyslipidaemia. Medical management of these men should therefore include endocrinological evaluation and follow-up after completion of infertility treatment.

High risk of azoospermia in men treated for childhood cancer

Childhood cancer survivors (CCS) have an increased risk of impaired spermatogenesis, but data regarding the disease- and treatment-related risk factors of azoospermia are scarce. Such information is crucial both for counselling CCS and for selecting patients for testicular tissue cryopreservation. The proportion of azoospermic men in CCS was 18% [95% confidence interval (CI): 12-26], specifically for leukaemias (19%; 95% CI: 5.5-42), Hodgkin's disease (53%; 95% CI: 29-76), non-Hodgkin's lymphoma (11%; 95% CI: 0.28-48) and testicular cancer (11%; 95% CI: 0.28-48). In CCS treated with high doses of alkylating agents, the proportion of azoospermic men was 80% (95% CI: 28-99) and if radiotherapy was used additionally, the proportion was 64% (95% CI: 35-87). In CCS with subnormal Inhibin B levels, the proportion of azoospermic men was 66% (95% CI: 47-81) and for those with elevated follicle-stimulating hormone (FSH) levels, the proportion was 50% (95% CI: 35-67). Among CCS with subnormal testicular volume (≤ 24 mL), azoospermia was found in 61% (95% CI: 39-80) of the cases. Most childhood cancer diagnoses are associated with an increased risk of azoospermia, especially in CCS receiving testicular irradiation, high doses of alkylating drugs and other types of cytotoxic treatment, if combined with irradiation. Inhibin B, FSH and testicular volume can be used as predictors for the risk of azoospermia.

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.

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.

Androgen receptor gene GGN repeat length and reproductive characteristics in young Swedish men

BACKGROUND

The human androgen receptor (AR) gene contains two polymorphisms of CAG and GGN repeats respectively. The GGN repeat function is still largely unknown and to date there are no in vivo data on this segment with respect to the general population.

METHODS

We investigated the impact of CAG and GGN repeats on male reproductive function, one by one and in interaction with each other, in 220 adolescent men from the general Swedish population. Physical examination and semen analysis, including accessory sex gland markers and measurement of reproductive hormone levels, were performed. Lifestyle-associated factors, including maternal smoking during pregnancy, were recorded. GGN and CAG repeat lengths were determined by sequencing.

RESULTS

GGN<23 was associated with lower semen volume when compared to GGN=23 (mean difference -0.6 ml, P=0.02) and GGN>23 (mean difference -0.9 ml, P=0.002). Men with GGN<23, exposed to maternal smoking during pregnancy, had higher body mass index compared to men with other GGN lengths, no matter whether their mother had smoked or not during pregnancy (mean difference 4.8 kg/m2, P<0.001).

CONCLUSIONS

Short GGN repeats seem to be associated with decreased semen volume, possibly due to suboptimal AR activity. Body composition may be influenced by the combination of fetal exposure to maternal smoking and certain AR genotypes.

Significant impact of 5alpha-reductase type 2 polymorphisms on sperm concentration and motility

Androgens, including 5alpha-dihydrotestosterone (DHT), are known to play a role for spermatogenesis and accessory sex gland function. The enzyme 5alpha-reductase (SRD5A) catalyses the conversion of testosterone to DHT. Our objective was to investigate whether polymorphisms in the SRD5A2 gene influence semen parameters in the general population. DNA from 182 Swedish military conscripts was examined for the A49T, V89L, and R227Q polymorphisms in the SRD5A type 2 gene. Ejaculates were analysed according to WHO guidelines. In addition, sperm motility was assessed using computer-aided sperm analysis (CASA). Seminal markers of epididymal (neutral alpha-glucosidase), prostatic (prostate specific-antigen and zinc), and seminal vesicles function (fructose) were measured. The A49TT-allele was associated with significantly higher sperm concentration compared with the wild type A-allele (mean: 102 x 10(6)/mL vs. 57 x 10(6)/mL, p = 0.02). The V89LV-genotype was correlated with significantly higher proportion progressive motile spermatozoa compared with the L-variant (mean: 55% vs. 48%, p = 0.04). The same trend was found regarding the CASA motile spermatozoa (mean: 52% vs. 41%, p = 0.02). No association between any of the polymorphisms and biochemical markers was found. SRD5A2 gene variants were associated with sperm concentration and motility, but not with epididymal and accessory sex gland markers. This effect on sperm parameters might therefore be exerted via a direct effect of DHT on spermatogenesis.

No association between mutations in the human androgen receptor GGN repeat and inter-sex conditions

The functional role of the GGN repeat in the human androgen receptor gene is unknown, although mutations in this region have been found in patients with inter-sex conditions. We have investigated the prevalence of GGN mutations in the androgen receptor in the Swedish population and their relation to male reproductive function. A physical examination and semen analysis was carried out in 223 men under medical examination before military service and in 94 men referred due to infertility and having sperm concentrations <5 x 10(6)/ml. The GGN and CAG repeats in the androgen receptor gene were directly sequenced. Both populations contained two predominant alleles of 23 and 24 GGN repeats, 83.8 and 90.5% respectively. Four mutations, three in the conscripts and one among the infertile men, were found, resulting in three GGC to GGT substitutions and one GGT to GGC substitution. None of the men presented with genital abnormalities, but two conscripts had low ejaculate volumes (0.3 and 0.9 ml). All men carrying a mutation also had GGN lengths >or=24. Three subjects with GGN >24, with no mutations and with normal seminal volumes, were also found. Our findings indicate that point mutations in the GGN repeat are frequently found in the general male population (1.3%; 95% CI: 0.3-3.9%), but are usually not associated with profound changes in the male phenotype.

The impact of testicular and accessory sex gland function on sperm chromatin integrity as assessed by the sperm chromatin structure assay (SCSA)

BACKGROUND

The sperm chromatin structure assay (SCSA) provides an objective assessment of sperm chromatin integrity, which is essential for normal sperm function. SCSA is valuable as a fertility marker in epidemiological studies and in the clinical situation. Little is known about the impact of testicular and post-testicular function on SCSA parameters.

METHODS

Ejaculates from 278 military conscripts of median age 18.1 (range 18-21) years were included. Levels of reproductive hormones, the length of the CAG repeat of the androgen receptor gene, sperm concentration, abstinence period and biochemical parameters of epididymal and accessory sex gland secretions were correlated to the SCSA parameters, DNA fragmentation index (DFI) and highly DNA stainable (HDS) cells.

RESULTS

Negative correlations were found between sperm concentration and DFI (r = -0.119, P = 0.049) and HDS (r = -0.513, P < 0.0001). DFI was negatively correlated with levels of estradiol (r = -0.19, P = 0.002) and free testosterone (r = -0.13, P = 0.03). DFI also correlated positively with abstinence time (r = 0.17, P = 0.005), and with seminal concentrations of fructose (r = 0.18, P = 0.004) and zinc (r = 0.12, P = 0.04).

CONCLUSIONS

Sex steroid production, spermatogenic function, abstinence time and seminal vesicle function appear to impact on sperm chromatin integrity and thereby on sperm fertilizing capacity. These findings may improve present understanding of the pathophysiology of male infertility.

A novel mutation (N233K) in the transactivating domain and the N756S mutation in the ligand binding domain of the androgen receptor gene are associated with male infertility

OBJECTIVE

Resistance to androgens has been suggested as a possible cause of male infertility. This hypothesis is based mainly on binding studies in genital skin fibroblasts but the molecular evidence is sparse.

DESIGN

Molecular studies of the androgen receptor gene were performed in 10 azoo- or oligozoospermic men, presenting with clinical signs of low androgen activity-poor virilization and high serum LH despite elevated testosterone levels, but without genital malformations.

PATIENTS

Ten men with serum LH >10 IU/l and testosterone >30 nmol/l as well as a low sperm concentration < 20 x 106/ml.

MEASUREMENTS

Genomic DNA was prepared from peripheral leucocytes and PCR-amplification of the coding region of androgen receptor was performed, followed by direct sequencing. Identified mutations were reconstructed by site-directed mutagenesis and the functional properties of the mutants were analysed, using transient expression in COS-1 cells and subsequent transactivation assays. Hormone binding assays were performed in genital skin fibroblasts from the patients.

RESULTS

Two of the 10 men were shown to have a mutation in the androgen receptor gene. Subject 1, who presented with azoospermia, serum testosterone (T) 50 nmol/l and LH 20 IU/l, had a mutation in exon 1, changing amino acid asparagine 233 to lysine (N233K). In fibroblasts cultured from genital skin, the receptor affinity for 5alpha-dihydrotestosterone (DHT) was normal as compared to healthy controls, but the receptor-hormone complex was thermolabile at 42 degrees C. Subject 2 exhibited severe oligozoospermia and a similar endocrine pattern (T = 50 nmol/l and LH = 25 IU/l). He had a mutation in exon 5 changing asparagine 756 to serine (N756S). The affinity for DHT in cultured genital fibroblasts from this patient was reduced. Transactivation was abnormal for both mutants, N233K reaching 46% and N756S 38% of wild type activity when stimulated with 10 nmol/l DHT.

CONCLUSIONS

Androgen receptor mutations may affect sperm production without resulting in genital malformations. Thus, in infertile men with a clinical presentation of poor androgen activity and an endocrine profile compatible with androgen resistance, mutations in the androgen receptor should be taken into consideration.

Preserved male fertility despite decreased androgen sensitivity caused by a mutation in the ligand-binding domain of the androgen receptor gene

Mutations in the androgen receptor gene are considered as incompatible with preservation of fertility and have been suggested as a cause of male infertility. Two adult brothers, referred because of gynecomastia and hormonal levels in serum indicating androgen insensitivity (high sex hormone-binding globulin, and LH levels, despite extremely high testosterone concentration), turned out to be relatives to a third young man, referred independently of the two others and exhibiting identical clinical and hormonal stigmata. In all three men, we found a C-->A substitution at position 2470 (exon 7) in the androgen receptor gene, leading to a Gln824Lys mutation in the ligand-binding domain of the receptor. Exploring the family history revealed that their grandfathers, on their mothers' side, were brothers; and the Gln824Lys mutation was also found in the one of them who was still alive. Binding studies with the mutant receptor in transfected COS-7 cells, with mibolerone as ligand, exhibited equal Kd (0.7 vs. 1.0 nmol/ L), IC50 (0.8 vs. 1.1 nmol/L), and maximum binding (7.1 vs. 8.9 fmol/ 10(6) cells), as compared with the wild-type (WT) receptor. In a chloramphenicol acetyl transferase trans-activation assay, the activity of the mutant receptor was identical to that of the WT, when the synthetic androgen R1881 was'used as a ligand; but with dihydrotestosterone, in concentrations up to 10 nmol/L, the activity of Gln824Lys mutated receptor was 10-62% of the WT variant. Thus, Gln824Lys mutation was found, both in vivo and in vitro, to cause slight impairment of receptor function but was compatible with preservation of male fertility. The patients inherited the mutation from their grandfathers through their mothers, and one of the young men possessing the mutation has fathered a daughter.