Plasma concentration of testosterone, dihydrotestosterone, testosterone-oestradiol binding globulin, and pituitary gonadotrophins in the syndrome of male pseudo-hermaphroditism with testicular feminization

Molecular biology of androgen insensitivity

Androgen insensitivity syndrome (AIS) is the most common specific cause of 46,XY disorder in sex development. The androgen signaling pathway is complex but so far, the only gene linked with AIS is the androgen receptor (AR). Mutations in the AR are found in most subjects with complete AIS but in partial AIS, the rate has varied 28-73%, depending on the case selection. More than 400 different mutations in AR leading to AIS have been reported. Most mutations are missense substitutions located in the ligand binding domain of the receptor. However, when systematically screened, a substantial amount of mutations can be detected also in the N-terminal domain encoded by exon 1. Within this exon lie two trinucleotide, CAG and GGN repeat regions which are polymorphic in length. Their role in androgen insensitivity is somewhat unclear. Recent advances in protein modeling have resulted in better understanding of the mechanism of known AR mutations.

Mutational Analysis of Androgen Receptor (AR) Gene in 46,XY Patients with Ambiguous Genitalia and Normal Testosterone Secretion: Endocrinological Characteristics of Three Patients with AR Gene Mutations

The prevalence of abnormalities in androgen receptor gene (AR) among patients with ambiguous genitalia is unknown. Moreover, endocrinological data from prepubertal patients with AR mutation are very limited. Thus, the aim of this study was to examine the prevalence of abnormalities in AR among patients with both ambiguous genitalia, which was defined as a combination of two or more genital abnormalities (i.e. hypospadias, microphallus (penile length < 25 mm), hypoplastic scrotum, bifid scrotum, undescended testis) in this study, and normal to elevated T levels. We also compared the endocrinological data of prepubertal patients with AR mutation and ambiguous genitalia with that of those without the AR mutation. We screened 26 Japanese prepubertal 46,XY patients (five from three families were included) with both ambiguous genitalia and normal to elevated T levels. Mutations in AR were found in three (two of the three were related). Among the 23 patients without mutation in AR, the steroid 5-alpha-reductase 2 gene (SRD5A2) was also examined in eight patients with elevated T/dehydrotestosterone ratio after the hCG (>10) or with undervirilized family members. No mutation in SRD5A2 was found. Characteristics of the three patients with mutation in AR were compared with the 23 patients without mutation. In two patients, basal T levels (0.3, 0.2 ng/ml) and peak T levels after the hCG tests (8.3, 8.5 ng/ml) tended to be higher, and the peak LH/ peak FSH ratios after the GnRH tests (4.6, 4.0) were higher than in patients without mutation, at the ages of 1 yr and 9 mo and 3 yr and 8 mo, respectively. In conclusion, an abnormality in either AR or SRD5A2 was not common among patients with ambiguous genitalia and normal testosterone secretion. Elevated peak LH/peak FSH ratio (≥4) after the GnRH test in addition to detectable basal T levels and elevated peak T levels after the hCG test may infer AR abnormality in prepubertal patients with ambiguous genitalia at the age of one and over, although further study is needed, because our data were limited.

Puberty in Subjects with Complete Androgen Insensitivity Syndrome

BACKGROUND

Androgen receptor defects affect the regulation of the gonadotropic axis. However, little is known about the timing of pubertal maturation in complete androgen insensitivity syndrome (CAIS).

AIMS

To evaluate growth, skeletal maturation and gonadotropin and sex steroid secretion in patients with CAIS and intact gonads at puberty.

METHODS

Clinical, auxological and hormonal evaluation of 9 patients with CAIS from birth up to 17 years of age, prior to gonadectomy, in a single institution, retrospective study.

RESULTS

Breast development occurred at a median age of 11.1 years, thumb sesamoid appeared at 11.5 years, and peak height velocity at 12.3 years, all consistent with average female values. However, median adult male height (+1.2 SDS) was closer to the patients' male target height (-0.3 SDS). Plasma testosterone levels rose early compared to normal boys. LH (basal and GnRH-stimulated) increased rapidly, above normal male values, in early puberty.

CONCLUSIONS

This retrospective evaluation of a limited number of cases with a heterogeneous pattern of follow-up suggests that patients with CAIS may enter puberty at an age closer to female standards. These results imply a major role of direct androgen action, in utero or in early life, in determining the pattern of pubertal gonadotropin maturation.

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.

Induction of Leydig cell adenomas by ammonium perfluorooctanoate: a possible endocrine-related mechanism

Ammonium perfluorooctanoate (C8) produced an increased incidence of Leydig cell adenomas in Crl:CD BR (CD) rats fed 300 ppm for 2 years. A hormonal (nongenotoxic) mechanism was examined since C8 was negative in short-term tests for genotoxicity. Adult male CD rats were gavaged with either 0, 1, 10, 25, or 50 mg/kg C8 for 14 days. In addition, a control group was pair-fed to the 50 mg/kg C8 group. A dose-dependent decrease in body and relative accessory sex organ (ASO) weights was seen, with the relative ASO weights of the 50 mg/kg group significantly less than those of the pair-fed control. Serum estradiol levels were elevated in the 10, 25, and 50 mg/kg C8-treated animals. Estradiol levels in the 50 mg/kg C8 group were 2.7-fold greater than those in the pair-fed control. The increase in serum estradiol levels occurred at the same dose levels as the increase in hepatic beta-oxidation activity. A statistically significant downward trend with dose was seen in serum testosterone levels when compared with the ad libitum control. However, when the 50 mg/kg C8-treated rats were compared with their pair-fed control, no significant differences were seen. Challenge experiments, which can identify the presence and location of a lesion in an endocrine axis, were undertaken to clarify the significance of this downward trend in serum testosterone following C8 exposure. In the challenge experiments, adult CD rats were gavaged with either 0 or 50 mg/kg C8 for 14 days. One hour before termination, rats received either a human chorionic gonadotropin (hCG), gonadotropin-releasing hormone (GnRH), or naloxone challenge. Following hCG challenge, serum testosterone levels in the 50 mg/kg C8 were significantly decreased (50%) from those in the ad libitum controls. Similar decreases, although not significant, were seen in serum testosterone following GnRH and naloxone challenge. The challenge experiments suggest that the decrease in serum testosterone following C8 exposure is due to a lesion at the level of the testis. In addition, progesterone, 17 alpha-hydroxyprogesterone, and androstenedione were examined in the 50 mg/kg C8-treated males following hCG challenge. A 60% decrease was observed in androstenedione levels in the C8-treated animals from those in the ad libitum controls; no other differences were seen. These data suggest that the decrease in serum testosterone following hCG challenge may be due to a decrease in the conversion of 17 alpha-hydroxyprogesterone to androstenedione. The observed effects described above can be attributed to the elevated serum estradiol levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Deletion of the steroid-binding domain of the human androgen receptor gene in one family with complete androgen insensitivity syndrome: evidence for further genetic heterogeneity in this syndrome

The cloning of a cDNA for the human androgen receptor gene has resulted in the availability of cDNA probes that span various parts of the gene, including the entire steroid-binding domain and part of the DNA-binding domain, as well as part of the 5' region of the gene. The radiolabeled probes were used to screen for androgen receptor mutations on Southern blots prepared by restriction endonuclease digestion of genomic DNA from human subjects with complete androgen insensitivity syndrome (AIS). In this investigation, we considered only patients presenting complete AIS and with the androgen receptor (-) form as the most probable subjects to show a gene deletion. One subject from each of six unrelated families with the receptor (-) form of complete AIS and 10 normal subjects (6 females and 4 males) were studied. In the 10 normal subjects and in 5 of the 6 patients, identical DNA restriction fragment patterns were observed with EcoRI and BamHI. In one affected individual, a partial deletion of the androgen receptor gene involving the steroid-binding domain was detected. Analysis of other members of this family confirmed the apparent gene deletion. Our data provide direct proof that complete AIS in some families can result from a deletion of the androgen receptor structural gene. However, other families do not demonstrate such a deletion, suggesting that point mutations (or small, undetectable deletions) may also result in the receptor (-) form of complete AIS, adding further to the genetic heterogeneity of this syndrome.

The relationship between sex steroids and sex-hormone-binding globulin in plasma in physiological and pathological conditions

Physiological and many pathological changes in plasma sex-hormone-binding globulin (SHBG) levels have been attributed to the opposing effects of androgens which lower, and oestrogens which elevate, levels. We examined four clinical situations in which changes in SHBG levels may not be explained by sex steroid alterations. (1) Dexamethasone caused an increase in SHBG levels in hyperandrogenaemic hirsute women whether or not androgens were suppressed. (2) In male patients with untreated isolated gonadotrophin deficiency there was a highly significant correlation between SHBG levels and age, but there was no relationship between the levels of SHBG and those of plasma testosterone, androstenedione or DHEAS. (3) Two 46-XY siblings, phenotypic female subjects with complete androgen insensitivity, demonstrated a marked decline in SHBG levels between the ages of 9-13 and 12-16 years. (4) SHBG was suppressed in obese oligomenorrhoeic women while plasma concentrations of testosterone, androstenedione and oestradiol were normal and that of oestrone was elevated; however, the testosterone:SHBG ratio, an index of free testosterone, was elevated. These observations indicate that the decline in SHBG levels which normally occurs in men during the second decade of life is independent of androgen activity and is under the influence of as yet unidentified factors. Glucocorticoids in small doses under the influence of as yet unidentified factors. Glucocorticoids in small doses increase SHBG levels independently of sex steroid alterations while elevated free testosterone concentration may contribute to suppression of SHBG in obesity.

Tentative evidence of Y-linked statural gene(s). Growth in the testicular feminization syndrome

The linear growth data of 48 XY individuals, presumed to be androgen-insensitive as a consequence of the testicular feminization syndrome, were found to be similar to normal male standards and tall for normal female standards. These data are interpreted as evidence for one or more Y-linked gene function(s) which augment stature independently of testosterone effects.

Androgen receptors

Testosterone and its active metabolite dihydrotestosterone exert their influence on target cells through a specific intracellular protein receptor. Structural abnormalities of this receptor lead to a diminished androgen action within the cell and result in the syndrome of androgen insensitivity. Androgen insensitivity is classified on the basis of whether the insensitivity is complete or partial and whether the androgen receptor is normally present (AR(+)), absent (AR(-)) or diminished (AR(+/-)). All patients with androgen insensitivity have normal or high plasma levels of testosterone and elevated serum LH. Patients with complete androgen insensitivity are phenotypically female. The clinical presentation of partial androgen insensitivity is variable, ranging from a minimal amount of virilization to a completely masculine appearance. All patients described with a syndrome of androgen insensitivity are infertile. The influence of androgen receptor function in the pathogenesis of benign prostatic hypertrophy is being investigated. Androgen receptor content is also being studied as a possible marker of responsiveness to hormonal therapy in prostatic carcinoma.

Testicular function in post pubertal male pseudohermaphroditism

Testicular endocrine function was studied in twelve post pubertal patients with male pseudohermaphroditism and 46 XY chromosomal constitution. Patients were divided into three groups, four subjects who became feminized during puberty, five who became masculinized during puberty and three who were castrated before puberty. Serum dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, androstendione, testosterone, dihydrotestosterone, LH and FSH were determined by radioimmunoassay. Patients of the first group had the clinical characteristics of testicular feminization secondary to absence of the androgen receptor. One of the five patients of the second group had deficient testosterone secretion but no enzymatic defect could be demonstrated. One of the subjects castrated before puberty had a deficiency in 17,20-desmolase. Therefore, evidence of a failure of the fetal testes could be found in only two of the twelve patients studied.

Search for progesterone receptors in testes from various animal species

Using [3H]R5020 as binding probe, we have looked for the presence of progesterone receptors in testis cytosol from a few vertebrate species ranging from the turtles to the humans. In addition, we have tested in the rat several experimental conditions potentially susceptible to induce progesterone receptors. With the exception of chicken, tfm patients and possibly the frogs, progesterone receptors could not be conclusively demonstrated in any of the other animal species tested nor could they be induced in the rat. Surprisingly, they were not present in Stanley-Grumbeck pseudohermaphrodite rats. In chicken testes, the levels of progesterone receptor were variable (3--45 fmol per mg prot.) in the adults and high (87 fmol per mg prot.) in one-day-old animals. The presence of progesterone receptor, a marker of estradiol action in many estrogen-target tissues, seems to be parallel to the capacity of chicken testes for sex reversal under the influence of estrogens. In human tfm, the presence of these receptors could also indicate that the gonads are estrogen-sensitive or that they were so during embryonic life although the nature of estrogenic action is not known.

Preliminary studies on streoid-binding proteins in human testes of testicular feminization syndrome

This study was designed to detect either 5alpha-dihydrotestosterone (DHT) or 17beta-estradiol (E2)-binding protein in the testes of a 1-year-old patient with testicular feminization syndrome (TFS) and in the testes of patients with prostatic cancer. Sucrose gradient analyses revealed E27S protein binding (but no such 7S protein binding of DHT) in the testes of the patient with TFS, but both E2 and DHT 7 S protein binding was observed in normal senile testes. The dissociation constants (Kd) were measured by charcoal adsorption. The Kd of E2 protein binding in both testes of different status was approximately 1.3 x 10(-9) M, and the Kd of DHT protein binding was 2.0 x 10(-9) M in the senile testes. A ligand specificty study indicated characteristics of both E2 and DHT receptors in the senile testes. It is speculated that a deficiency of androgen receptor and the presence of estrogen receptor in the testes of patients with TFS lead to insensitivity to androgen as a result of the androgen receptor deficiency and to sensitivity to estrogen as a result of the presence of the estrogen receptor.

Endocrine studies in male pseudohermaphroditism in childhood and adolescence

The clinical and endocrine features of fifty cases of male pseudohermaphroditism and XY karyotype aged from 6 months to 20 years have been studied. Thirty-two subjects were pre-pubertal and eighteen, of whom ten developed gynaecomastia, were pubertal. A definite aetiology was established in 12%. 4% had deficient testosterone biosynthesis and 8% mixed gonadal dysgenesis. In the remaining 88% an aetiology of androgen unresponsiveness at the target areas is suggested. Hormonal investigations in these subjects showed that before puberty basal plasma testosterone and oestradiol were slightly but significantly elevated, whereas testosterone response to stimulation with human chorionic gonadotrophin was significantly diminished. In the pubertal subjects basal plasma testosterone, oestradiol, serum binding capacity of testosterone-oestradiol binding globulin and basal plasma LH were significantly elevated. These hormonal features in pubertal or post-pubertal male pseudohermaphrodites appear to be characteristic of androgen unresponsiveness. The presence in addition of elevated basal plasma testosterone and oestradiol in the pre-pubertal subjects suggest that some of these findings may be presented from early childhood.

Partial androgen insensitivity: the Reifenstein syndrome revisited

We investigated eight patients with the Reifenstein syndrome to define the hormonal basis for this condition. The patients had normal or elevated concentrations of plasma androgens, normal production rates of testosterone and dihydrotestosterone, elevated serum levels of luteinizing hormone and normal 5alpha-reductase activity in skin fibroblasts. These findings indicate that the syndrome results from defective androgen action rather than from decreased androgen synthesis. The term "partial androgen insensitivity syndrome" describes this condition more accurately than a term based on clinical phenotype. Dihydrotestosterone binding studies in skin fibroblasts demonstrated two genetic variants similar to those reported in complete androgen insensitivity syndrome. One patient had a partial deficiency of cytoplasmic dihydrotestosterone binding, and four others had normal binding activity. The cause of the androgen insensitivity in the last four cases is unknown. Treatment with testosterone suppressed serum luteinizing hormone levels and promoted mild virilizing effects.

H-y antigen: expression in human subjects with the testicular feminization syndrome

Androgen-insensitive subjects with a 46,XY karotype develop as phenotypic females despite presence of testes. The white blood cells of these females type H-Y antigen-positive indicate that expression of the H-Y cell surface component is androgen-independent.

Male pseudohermaphroditism due to steroid 5-alpha-reductase deficiency

A new inherited form of male pseudohermaphroditism has been investigated in a pedigree of 24 families with 38 affected males. At birth, the affected males (46 XY) have a clitoral-like phallus, bifid scrotum and urogenital sinus. The testes are in the inguinal canals or labial-scrotal folds. The Wolffian structures are normally differentiated; there are no Mullerian structures. At puberty a muscular male habitus develops with growth of the phallus and scrotum, voice change and no gynecomastia. The subjects have erections, ejaculations and a libido directed towards females. They have decreased body hair, a scant to absent beard, no temporal hair line recession and a small prostate. Testicular biopsy reveals a normal testis. The mean plasma T levels in affected adults are significantly higher, and the mean plasma DHT levels are significantly lower when compared to those in normal subjects. The plasma T:DHT ratios range from 35 to 84 compared to 8 to 16 in normal subjects. After the administration of hCG, the T:DHT ratios in affected male children range from 74 to 162 compared to 3 to 26 in the control subjects. In affected adults, mean plasma LH and FSH levels are significantly higher than in normal subjects. In the affected subjects, the metabolic clearance rates of T and DHT are normal, but the conversion ratio of T to DHT is less than 1 per cent. The endogenous mean urinary E:A and E-OH:A-OH ratios, and the urinary E:A and E-OH:A-OH ratios after the infusion of radioactive T are significantly higher than in normal males. Inheritance is autosomal recessive with some sibling sisters showing the same biochemical defect, and obligate carrier parents showing an intermediate defect. These data support our thesis that the defect in these male pseudohermaphrodites is secondary to decreased steroid delta 4-5 alpha-reductase activity. The affected subjects provide a clinical model for delineating the roles of T and DHT in sexual differentiation and development. This entity also demonstrates an inherited disorder of steroid metabolism in which the basic enzyme deficiency resides in the target tissues.

Ultrastructural study of testis in testicular feminization

Testicular tissue was investigated by electron microscopy in a case of testicular feminization. The seminiferous tubules were lined by spermatogonia and by Sertoli cells. Spermatocytic maturation was not observed. Leydig cells were numerous and contained well developed, abundant vesicular smooth-surfaced endoplasmic reticulum and large mitochondria with tubulovesicular cristae. Reinke crystalloids were absent. The ultrastructural findings were consistent with the assumption that Leydig cells were under adequate stimulation and were in a stage of active secretion. Hence, the results seem to indicate that testicular endocrine function was maintained in the studied case.

Testicular feminization syndrome: current clinical considerations

The testicular feminization syndrome (TFS) in its complete form results in total feminization due to a nuclear inaction of androgens, and the female role should be supported with postpubertal orchiectomy to avoid the risk of malignancy. Incomplete forms of the syndrome (ITFS) include Type I n which some degree of masculinization may be observed, prompting earlier gonadectomy, and Type II or pseudovaginal perineoscrotal hypospadias (PPSH) which is always characterized by pubertal masculinization, necessitating management and support of these patients as males. Other intersex abnormalities which must be differentiated include true hermaphroditism, the Swyer syndrome, males with 17-ketosteroid reductase deficiency, and Reifenstein's syndrome.

Radioimmunoassay of plasma dihydrotestosterone in normal and hypogonodal men

A radioimmunoassay for determination of dihydrotestosterone (DHT) in man is described. After extraction from plasma, DHT is separated by paper chromatography. The radioimmunoassay is performed using an antiserum to dihydrotestosterone-3-oxime-BSA and a charcoal-dextran mixture is used to separate the free from the bound fraction. The reliability criteria of the method in terms of precision, accuracy, sensitivity and specificity have been evaluated. The mean level of DHT in plasma samples from young (age 21-37) and old (age 65-90) normal men is respectively (mean+/-SD) 54-7+/-19 ng/dl (n = 17) and 39-1+/-19 ng/dl (n = 14). The difference is statistically significant (P less than 0-01). The values found in seven patients with Klinefelter's syndrome (21-0+/-6 ng/dl) are significantly lower than normal young subjects (P less than 0-01). Lastly, the DHT levels found in a mixed group of male hypogonadism (azoospermia, due to tubular failure, germinal cell aplasia and anorchia) are reported.

Studies of in vitro steroid metabolism by testis tissue from 'complete' and 'incomplete' forms of testicular feminization

The in vitro steroid metabolism of testicular tissue from seven cases of testicular feminization was studied. Using radioactive steroid substrates of both C21 and C19 configurations, kinetic studies of these tissues showed that the major pathway of testosterone production was via the delta5 pathway, i.e. pregnenolone leads to 17 alpha-hydroxypregnenolone leads to dehydroepiandrosterone leads to androstenedione and androstenediol leads to testosterone, with the accumulation of dehydroepiandrosterone and androstenediol. This accumulation of dehydroepiandrosterone and androstenediol does not occur in similar incubations of normal human testis tissue. The seven cases of testicular feminization were classified as 'complete' or 'incomplete' forms of the syndrome by reference to clinical data and the histology of the testicular tissue. It was concluded that the biochemical differences between the two forms of the syndrome were the greater production and accumulation of C21 and C19 delta 4 steroids from the C21 and C19 delta 5 steroid precursors indicating the relatively greater activity of the C21-3beta-hydroxysteroid dehydrogenase-isomerase enzyme in the 'incomplete' form.