A clinician looks at androgen resistance

Baldness, acne and testicular germ cell tumours

Androgen levels during critical periods of testicular development may be involved in the aetiology of testicular germ cell tumours (TGCT). We evaluated the roles of adolescent and early adult life correlates of androgen exposure and TGCT in a hospital-based case-control study. TGCT cases (n=187) and controls (n=148), matched on age, race and state of residence, participated in the study. Unconditional logistic regression was used to estimate associations between TGCT and male pattern baldness, severe acne, markers of puberty onset and body size. Cases were significantly less likely to report hair loss than controls [odds ratio (OR): 0.6; 95% confidence interval (CI): 0.4, 1.0]. Amount of hair loss, increasing age at onset and increasing rate of loss were all inversely associated with TGCT (rate of hair loss: p-trend=0.03; age at onset: p-trend=0.03; amount of hair loss: p-trend=0.01). History of severe acne was inversely associated with TGCT (OR: 0.5; 95% CI: 0.3, 0.9) and height was positively associated with TGCT (p-trend=0.02). Increased endogenous androgen levels during puberty and early adulthood may be associated with a decreased risk of TGCT. Additional studies of endogenous hormone levels during puberty and early adult life are warranted, especially studies evaluating the role of androgen synthesis, metabolism and uptake.

Comparison of the molecular consequences of different mutations at residue 754 and 690 of the androgen receptor (AR) and androgen insensitivity syndrome (AIS) phenotype

OBJECTIVE

Androgen insensitivity syndrome (AIS) is associated with mutations throughout the androgen receptor (AR) gene. Different mutations at the same codon have been identified in individuals with various phenotypes suggesting the nature of the codon substituted may influence the degree of AIS. We investigated if phenotype could be predicted by comparing the functionality of AR mutations with those at the same codon of known phenotype.

PATIENTS

We identified patients from the Cambridge Disorders of Sex Development Database with the AR substitutions: Phe754Ser with microphallus without hypospadias and Asp690Val with complete AIS. Mutations Phe754Leu, Phe754Val and Asp690deletion (Asp690del) have previously been reported to be associated with different degrees of AIS.

DESIGN

We characterized the functional properties of Phe754Ser, Phe754Leu, Phe754Val, Asp690Val and Asp690del receptor mutants in vitro and used the crystal structure of the AR ligand binding domain to model the mutations.

RESULTS

The receptor mutants Phe754Ser, Phe754Leu and Phe754Val bound androgen with decreasing affinity, while Asp690Val showed reduced affinity compared to Asp690del. A similar pattern of reduced activation was seen on androgen responsive elements. We suggest how the mutations could affect AR structure, resulting in the observed phenotypes.

CONCLUSIONS

The relative functional properties of Phe754 and Asp690 mutant AR receptors correlate broadly with their specific phenotypes. Therefore, comparing the molecular consequences of novel mutations with others at the same codon may be a useful aid to AIS patient management, particularly for sex of rearing decisions when prediction of functionality is important.

Endocrine manipulation in male infertility

Endocrine therapy for male infertility is broadly categorized as specific or nonspecific therapy. Although uncommon, primary endocrine diagnoses in infertile men are amenable to targeted therapy. The efficacy of empiric endocrine therapy for idiopathic male infertility, however, has not been demonstrated conclusively by clinical trials. With better understanding of the underlying pathophysiology of idiopathic male infertility, careful evaluation of endocrine therapy in well-selected treatment groups and well-designed randomized, controlled trials is warranted. Although empiric endocrine therapy for idiopathic male infertility has been largely replaced by assisted reproductive techniques, both treatment modalities could play a role, perhaps as combination therapy.

Primary amenorrhea in a young Polish woman with complete androgen insensitivity syndrome and Sertoli-Leydig cell tumor: identification of a new androgen receptor gene mutation and evidence of aromatase hyperactivity and apoptosis dysregulation within the tumor

Primary amenorrhea in 46,XY females can be due to complete androgen insensitivity syndrome (CAIS), pure gonadal dysgenesis, 17-hydroxysteroid dehydrogenase deficiency, or mixed gonadal dysgenesis. The present paper describes a new de novo non-sense mutation in exon 1 (K141Z) of the androgen receptor gene (AR) and the expression in CAIS testis of aromatase, estrogen receptors, as well as proliferation- and apoptosis-associated proteins. CAIS is a rare disease characterized by absent virilization in 46,XY individuals and the development of a female phenotype despite normal or even elevated androgen levels. CAIS is usually caused by a mutation in AR, which leads to organ resistance to androgens. Testicular tumors such as Sertoli-Leydig cell tumor often develop in patients with CAIS. The immunohistochemical findings in the testes of our CAIS patient suggest that the high expression of aromatase and other molecular changes in the testis may be responsible for pubertal breast development and the increased risk of testicular tumor.

Impaired nuclear translocation, nuclear matrix targeting, and intranuclear mobility of mutant androgen receptors carrying amino acid substitutions in the deoxyribonucleic acid-binding domain derived from androgen insensitivity syndrome patients

CONTEXT

Recent imaging studies revealed that androgen receptor (AR) is ligand-dependently translocated from the cytoplasm into the nucleus and forms intranuclear fine foci. In this study, we examined whether intracellular dynamics of mutant ARs detected in two androgen insensitivity syndrome (AIS) patients was impaired.

OBJECTIVE

ARs with mutations in the DNA-binding domain were functionally characterized and compared with the wild-type AR.

PATIENTS

In a complete AIS patient (subject 1), cysteine residue 579 in the first zinc finger motif of AR was substituted for phenylalanine (AR-C579F). Another mutation (AR-F582Y) was found in a partial AIS patient (subject 2).

RESULTS

AR-F582Y retained less than 10% of the transactivation activity of the wild-type AR, whereas no ligand-dependent transactivation was detected for AR-C579F. Image analyses of the receptors fused to green fluorescent protein showed that the wild-type AR was ligand-dependently translocated into the nucleus in which it formed fine subnuclear foci. Surprisingly, after the addition of dihydrotestosterone, the two mutant ARs initially formed large cytoplasmic dots, many of which were found to be close to mitochondria by electron microscopy. Subsequently, a part of the ligand-bound mutant ARs gradually entered the nucleus to form a smaller number of larger dots, compared with the wild-type AR. Fluorescence recovery after photobleaching analysis revealed that the intranuclear mobility of the mutant ARs decreased, compared with that of the wild-type AR.

CONCLUSIONS

These results suggest that the abnormal translocation, localization, and mobility of the mutant ARs may be the cause of AIS in these subjects.

Correlation between genotype, phenotype and sex of rearing in 111 patients with partial androgen insensitivity syndrome

OBJECTIVE

Partial androgen insensitivity syndrome (PAIS) is a heterogeneous group of intersex disorders characterized by a typical perineoscrotal hypospadias/micropenis phenotype, and a normal androgen-producing testis. Various mutations in the androgen receptor (AR) are known to cause PAIS. Phenotypic expression is widely variable and there are no agreed guidelines to determine the sex of rearing in individuals with borderline masculinization. We aimed to quantitatively assess the external genital phenotype in relation to AR genotype and sex of rearing and identify criteria that differentiate mutation positive (ARmt) from mutation negative (ARwt) PAIS patients.

PATIENTS AND DESIGN

Cases with a diagnosis of PAIS were identified from the Cambridge Intersex Database. An external masculinization score (EMS) was used to quantify the degree of undermasculinization. Family history of AIS and details of the sex of rearing were recorded. Androgen binding was analysed in fibroblasts obtained from genital skin biopsies and mutational analysis of the AR was performed on genomic DNA extracted from peripheral blood. EMS and sex of rearing were compared in cases with similar mutations reported on the McGill International Database.

RESULTS

Two hundred and sixty-three patients with PAIS were identified. Androgen receptor gene sequencing was performed in 111 patients. Twenty-seven (24%) had mutations. Family history of AIS was present in 61 and 21% of ARmt and ARwt patients, respectively. The median EMS was 3 in both groups. The majority of ARmt patients had abnormal binding and there was a tendency to a higher median testosterone rise on hCG stimulation in ARmt (9.3 nmol/l) compared with ARwt patients (6.9 nmol/l). All patients with EMS of 4 or more were raised as male but there was an overlap of sex of rearing in patients with an EMS less than 4. A wide variation of EMS in relation to genotype and sex of rearing was observed.

CONCLUSION

The phenotype in PAIS is extremely variable and is rarely predicted by the AR genotype. Apart from the family history, there are no specific criteria to differentiate ARwt from ARmt. Sex of rearing is not entirely dependent on the EMS. Cultural issues, other modifying genes and response to androgen trials might be influencing factors. Collaborative studies with uniform protocols are needed to investigate infants with PAIS. Documenting phenotype, surgical procedures and outcome criteria are necessary to enable decision-making on the sex of rearing in patients with a lower range EMS.

Function of androgen receptor in gene regulations

Most of the androgen actions are considered to be mediated by the androgen receptor (AR) of the target genes. The AR is composed of a fairly large molecule because of the long A/B domains of its N-terminal. However, the independent roles of the AR as well as those of the estrogen receptors largely remained unknown mainly due to the lack of the AR knockout (ARKO) mice line. We have succeeded in generating the ARKO mouse by means of a conditional targeting using the Cre/loxP system. The ARKO males grew healthily although they showed a typical feature of the testicular feminization mutation (Tfm) and the hormonal assay revealed significantly lower serum androgen and higher LH levels in comparison with those of the wild type (WT) males. The serum estrogen levels were, however, comparable between both the ARKO and the WT. Another hallmark of the ARKO males was a state of high bone turnover osteopenia, in which the acceleration in the bone resorption clearly exceeded the bone formation. Male-typical behaviors were disrupted in male ARKO mice. Aiming at a quick differentiation of an androgen-dependent polyQ disease such as Kennedy's disease, the authors also developed the Drosophila fly-eye model in which the wild type and the polyQ-expanded human AR (hAR) was induced in the eyes of Drosophila. When androgen was administered to the flies induced with the polyQ-expanded hAR, their optical nerves were devastated.

Endocrine causes of male infertility

Although endocrinopathies are not often seen in infertile men, these disorders are clinically significant; they often have potentially serious medical significance, regardless of fertility issues. Correction of these disorders represents a possible way to restore normal fertility for the male partner. Male fertility is critically dependent upon a normal hormonal milieu. The hypothalamic-pituitary-gonadal axis is quite sensitive to disruption by endocrine disorders and other generalized medical disorders. Thus, male infertility is occasionally the presenting sign for significant underlying medical disease; it is important to properly evaluate these patients.

[Total androgenic insensitivity syndrome. Presentation as giant inguinal mass]

The androgen insensitivity syndrome is the most frequent form of masculine psedohermafroditism. The affected patients present female phenotype without sexual ambiguity but with karyotype 46 XY. In this syndrome the frequency of malignización of the testicles increases progressively with the age, because of this, the importance of an earlier diagnosis. We present a case of later diagnosis late of the androgen insensitivity syndrome, that debut with a great inguinal mass.

A case of complete testicular feminization: laparoscopic orchiectomy and analysis of androgen receptor gene mutation

BACKGROUND

Analysis of an androgen receptor gene mutation and a bilateral laparoscopic orchiectomy were performed on a 19-year-old patient diagnosed as a case of complete testicular feminization.

METHODS

DNA sequencing of an androgen receptor gene mutation and laparoscopic orchiectomy were performed.

RESULTS

A novel point mutation substituting a proline residue (CCG) for a leucine residue (CTG) was observed in codon 892 of exon 8 in the hormone-binding domain of the androgen receptor gene. Bilateral intra-abdominal testes were resected uneventfully by means of laparoscopic orchiectomy.

CONCLUSION

We conclude that genetic analysis of androgen receptor gene mutation is essential for diagnosis of teon and laparoscopic orchiectomy is a useful therapeutic alteration as a minimally invasive treatment.

Assessment of the gonadotrophin-gonadal axis in androgen insensitivity syndrome

OBJECTIVE

To study the value of measuring serum luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone, and dihydrotestosterone (DHT) in androgen insensitivity syndrome (AIS).

DESIGN

Retrospective study of patients on a nationwide register of AIS.

PATIENTS

Sixty one cases of AIS with androgen receptor (AR) dysfunction (abnormalities of the AR gene and/or abnormal AR binding) were divided into three age groups: infants, < 1 year old; children, 1-13 years old; and postpubertal, > 13 years old.

MEASUREMENTS

Age, dose of human chorionic gonadotrophin (hCG) stimulation, pre-hCG and post-hCG serum testosterone values, serum DHT values, and serum LH and FSH values before and after LH releasing hormone (LHRH) stimulation.

RESULTS

In 23 of 30 infants testosterone was within age related reference ranges; six were above this range. The median testosterone rise following variable dosage of hCG was 9.5 times the basal value. The increment was not related to the hCG dose, age, or basal concentration of testosterone. The median basal and stimulated testosterone:DHT ratios were 2.5 and 6.1, respectively. The median increment in DHT was 2.2-fold. Seventeen of 18 FSH and 11 of 19 LH measurements were within age related ranges in infants; in seven patients LH values were above the range. LHRH stimulation performed in 39 patients showed an exaggerated LH in all age groups. The FSH response was not exaggerated in children.

CONCLUSION

Although a positive hCG test excludes biosynthetic defects of testosterone, an inadequate response does not exclude AIS. Basal LH and testosterone may not be raised during early infancy. An LHRH stimulation test might be useful for evaluating cases of suspected AIS presenting in mid-childhood.