Complete Testicular Feminization Research Articles

COMPLETE ANDROGEN INSENSITIVITY SYNDROME : A CASE REPPORT AND REVIEW OF LITERATURE

Complete androgen insensitivity syndrome or testicular feminization syndrome is the most common form of male pseudohermaphrodism, caused by a failure of androgen receptor binding. Patient with male genotype 46 XY, has a female morphotype with well developed external sexual organs. We report the case of two young patients aged 23 and 21 with a TF syndrome discovered during the exploration of primary amenorrhea. A bilateral orchiectomy was performed with institution of estrogen-progestogen hormone treatment.

Molecular defects of the androgen receptor.

Mutations in the androgen receptor (AR) gene cause a range of phenotypic abnormalities of male sexual development. At one end of the spectrum are individuals with complete androgen insensitivity (complete testicular feminization) who exhibit normal breast development and female external genitalia. At the other extreme are individuals with male phenotypes that are characterized by either subtle undervirilization or infertility. Studies in a number of different laboratories have identified mutations of the AR gene in subjects with androgen resistance syndromes. Defects that interrupt the AR open-reading frame have been traced to a number of distinct types of genetic alterations, have been identified in widely separated segments of the AR gene, and are invariably associated with the phenotype of complete androgen insensitivity. By contrast, mutations that cause single amino acid substitutions within the AR are localized to the DNA- or ligand-binding domains of the receptor protein and have been associated with the full range of androgen-resistant phenotypes. Regardless of the nature of the mutation, functional studies and assays of AR abundance suggest that the phenotypic abnormalities that result from mutation of the AR are the result of the impairment of receptor function, decreases in receptor concentration, or both.

Complete Androgen Insensitivity Syndrome with 45,XY,t(13q;14q) Translocation(Two cases).

We report 2 cases of complete androgen insensitivity syndrome from 1 family with 45, XY, t(13q; 14q) karyotype including complete testicular feminisation (TF) clinical features. The chromosomal translocation is not generally considered part of the clinic spectrum in this group patients and most possibly it is the first report in the literature.

The androgen receptor (AR) in syndromes of androgen insensitivity and in prostate cancer

The actions of androgens, principally testosterone and 5α-dihydrotestosterone, are mediated by a specific receptor protein, the androgen receptor (AR), which is encoded by a single-copy gene located on the human X-chromosome. This receptor protein is a prototypical member of the nuclear receptor family and modulates a range of processes during embryogenesis and in the adult. During embryogenesis, normal AR function is critical to the development of the male phenotype and defects of the AR cause a range of phenotypic abnormalities of male sexual development. Complete loss of AR function has been traced to a number of distinct types of genetic events, including abnormalities of mRNA splicing, the introduction of premature termination codons, and amino acid substitution mutations. An interesting subset of mutations is that in which the AR is completely undetectable using sensitive immunoassays. In all instances, these functional abnormalities are associated with a phenotype of complete androgen insensitivity (complete testicular feminization). By contrast, partial defects of AR function are almost invariably caused by amino acid substitutions within the DNA- and hormone-binding domains of the receptor protein. Such partial defects of receptor function may be caused by changes in either receptor function or receptor abundance. The alterations of AR function and expression that have been characterized in clinical prostatic cancers and in prostate cancer cell lines differ in several important respects. A number of studies have documented the emergence of considerable heterogeneity of AR expression at early stages in the development of prostate cancer. Despite these early changes of AR expression, a substantial body of information suggests that the AR is expressed in advanced forms of prostate cancer, in some cases as the result of amplification events. While infrequent in localized tumors, mutations of the AR have been identified in a number of advanced prostatic cancers and in some instances appear to alter the ligand specificity of the AR. Finally, it appears that other signaling pathways can act to influence AR function.

Male Pseudohermaphroditism Caused by Mutations of the Human Androgen Receptor1

A exert their effects in mediating the development of the normal male phenotype via a single receptor protein, the androgen receptor (AR), which is encoded on the X chromosome. Abnormalities that alter the function of this receptor result in a range of abnormalities of male phenotypic development. These phenotypes range from that of normal females (complete testicular feminization, complete androgen insensitivity) to those that are characterized by only minor degrees of undervirilization and/or infertility. The defects of receptor function that have been characterized fall into two major categories. The first are those that disrupt the primary sequence of the AR. These mutations can be due to the introduction of premature termination codons, frameshift mutations, deletions or insertions, or alterations of RNA splicing. The ARs that are produced as a result of these genetic alterations are uniformly associated with complete androgen resistance. The second, and most common type of AR mutation, is that which is caused by single amino acid substitutions within the AR protein. In contrast to the preceding category, mutations of this type may result in the full spectrum of androgen resistant phenotypes. These mutations cluster in two important domains of the receptor protein: the DNAand the hormonebinding domains. Substitutions in the DNA-bindingdomain act to impair the ability of the AR to recognize target sequences within or adjacent to androgen-responsive genes. The degree of impairment of DNA binding is directly related to the degree of impairment of receptor function. Amino acid replacements within the hormone-binding domain can have a range of effects on the binding of ligand by the AR. In some instances, the capacity to bind hormone is completely abolished, while in other instances, only subtle qualitative abnormalities of ligand binding can be detected. In all mutants containing amino acid substitutions within the hormone-binding domain, the ability to form stable ARhormone complexes determines the amount of receptor function that remains. The phenotype that is observed does not appear to correlate with the identity of the residue that is mutated or its replacement. Instead, the phenotype appears to be a reflection of the degree to which androgen action is impaired. As the level of mutant AR protein expressed is similar to that observed in normal subjects, this usually reflects the degree to which AR function is altered. The male hormones, androgens, control wide range of processes in the male during embryonic development and in postnatal life. During embryogenesis, the concerted actions of testosterone (T) and 5a-dihydrotestosterone (DHT) are critical to the virilization of the Wolffian duct structures and the external genitalia. Genetic defects that impair androgen synthesis or action will result in abnormalities of male phenotypic development in 46, XY individuals with testes (male pseudohermaphroditism). Among the potential etiologies, defects of the AR are among the most common.

THE INCIDENCE OF INTERSEXUALITY IN CHILDREN WITH CRYPTORCHIDISM AND HYPOSPADIAS: STRATIFICATION BASED ON GONADAL PALPABILITY AND MEATAL POSITION

Purpose The combined findings of cryptorchidism and hypospadias often indicate the existence of an intersex state. Testicular maldescent and incomplete tubularization of the urethral plate occur in a spectrum with the severity of the 2 processes likely dependent on the degree of pathophysiology in the androgenic hormonal axis. The incidence of intersexuality in children with undescended testes, hypospadias and otherwise nonambiguous male genitalia has been reported to be 27%. Although the likelihood of genotypic or gonadal ambiguity has previously been associated with meatal position in this population, to our knowledge our study is the first to evaluate the incidence of intersexuality relative to whether the undescended testis is palpable or nonpalpable. Materials and Methods The database at our hospital was searched for all cases of undescended testes (2,105) and hypospadias (1,057) between 1982 and 1996. Radiographic, histological and karyotypic data were compiled for all patients presenting with both diagnoses. Gonadal palpability (palpable versus nonpalpable) and meatal position (anterior versus mid versus posterior) were recorded and correlated with the likelihood of identifying an intersex condition. Ten boys with a diagnosis of undescended testes subsequent to inguinal hernial repair were excluded from study. Patients with congenital adrenal hyperplasia or complete testicular feminization were also excluded from study due to the clearly female appearance of the external genitalia. Statistical significance was assessed using Fisher's exact test. Results We identified 79 patients presenting with undescended testes, hypospadias and a phallus that was believed to be a possible penis. Intersex conditions were identified with nearly equal frequency in the 44 cases of unilateral (30%) and 35 of bilateral (32%) cryptorchidism. In the unilateral undescended testes group patients with a nonpalpable testis were at least 3-fold more likely to have an intersex condition than those with a palpable undescended testis (50 versus 15%, p = 0.02). In the bilateral group patients with 1 or more nonpalpable testes were also nearly 3-fold as likely to have an intersex condition than those with bilateral palpable undescended gonads (47 versus 16%, p = 0.07). Meatal position was graded as anterior in 33% of cases, mid in 25% and posterior in 41% with the more posterior location conferring a significantly greater likelihood of an intersex condition (anterior 2 of 26, mid 1 of 20 and posterior 21 of 33). Conclusions Gonadal palpability is an important predictor of an intersex state in unilateral and bilateral cases of cryptorchidism with hypospadias. Patients with an undescended testis that cannot be palpated are significantly more likely to have an intersex condition than those in whom the undescended testis may be palpated on physical examination. The severity of hypospadias likewise has a strong positive correlation with an intersex state.

Molecular defects of the androgen receptor

Defects of the androgen receptor cause a wide spectrum of abnormalities of phenotypic male development, ranging from individuals with mild defects of virilization to those with complete female phenotypes. In parallel with this phenotypic spectrum, a large number of different mutations have been identified that alter the synthesis or functional activity of the receptor protein. In many instances, the genetic mutations identified lead to an absence of the intact, full-length receptor protein. Such defects (splicing defects, termination codons, partial or complete gene deletions) invariably result in the phenotype of complete androgen insensitivity (complete testicular feminization). By contrast, single amino acid substitutions in the androgen receptor protein can result in the entire phenotypic spectrum of androgen resistant phenotypes and provide far more information on the functional organization of the receptor protein. Amino acid substitutions in different segments of the AR open-reading frame disturb AR function by distinct mechanisms. Substitutions in the DNA binding domain of the receptor appear to comprise a relatively homogeneous group. These substitutions impair the capacity of the receptor to bind to specific DNA sequence elements and to modulate the function of responsive genes. Amino acid substitutions in the hormone-binding domain of the receptor have a more varied effect on receptor function. In some instances, the resulting defect is obvious and causes an inability of the receptor to bind hormone. In other instances, the effect is subtler, and may result in the production of a receptor protein that displays qualitative abnormalities of hormone binding or from which hormone dissociates more rapidly. Often it is not possible to correlate the type of binding defect with the phenotype that is observed. Instead, it is necessary to measure the capacity of the receptor that is synthesized in functional assays in order to discern any type of correlation with phenotype. Finally, two types of androgen receptor mutation do not fit such a categorization. The first of these—the glutamine repeat expansion that is observed in spinal and bulbar muscular atrophy—leads to a reduction of receptor function that can be measured in heterologous cells or in fibroblasts established from such patients. The expression of ARs containing such expanded repeats in men is associated with a degeneration of motor neurons in the spinal cords of affected patients. Likewise, the alterations of androgen receptor structure that have been detected in advanced forms of prostate cancer also behave as gain-of-function mutations. In this latter type of mutation, the exquisite specificity of the normal androgen receptor is relaxed and the mutant receptors can be activated by a variety of steroidal and non-steroidal ligands.

The craniofacial complex in karyotype 46,XY females.

The craniofacial cephalometric dimensions, angles and dimensional ratios of five Finnish individuals with complete testicular feminization (CTF) were compared with their first-degree relatives and population female and male controls. The linear and angular measurements were made from standardized lateral cephalograms of patients and normal population controls from the 'Kvantti Study' series. The women with CTF tended to have cranial base and maxillary complex dimensions between those of the normal control females and males. Their mandibular corpus was found to be longer than in normal control females, while their ramus was shorter compared with that of normal males. They also showed a smaller sagittal length ratio of the maxilla to the mandible, a smaller ANB angle and a more acute gonial angle than in both normal control females and males. Comparison of the women CTF with their first-degree female relatives showed basically the same trends as when comparing them with normal female controls. As the phenotype in these females with CTF is due to insensitivity to, or lack of androgens, it is suggested that the presence of the Y chromosome in these females leads to craniofacial dimensions between those of normal females and males which influences the growth of the mandibular corpus. This follows the same general metric pattern that is observed in many of their adult head and body dimensions as well as in their dental arches.

Assessment of androgen receptor function in genital skin fibroblasts using a recombinant adenovirus to deliver an androgen-responsive reporter gene.

Mutations of the androgen receptor (AR) cause defects in virilization and can result in a spectrum of phenotypic abnormalities of male sexual development that includes patients with a completely female phenotype (complete testicular feminization) and individuals with less severe defects of virilization, such as Reifenstein syndrome. These phenotypes are not specific for mutations of the AR gene, however, and defects in other genes can also result in similar abnormalities of male development. For this reason, the diagnosis of an AR defect is laborious and requires data from endocrine studies, the family history, and in vitro binding experiments. To assist in the evaluation of patients with possible AR defects, we previously employed the use of a recombinant adenovirus to deliver an androgen-responsive gene into fibroblast cultures to assay AR function in normal subjects and patients with complete forms of androgen resistance. Although these studies demonstrated measurable differences between these two groups of subjects, we did not assay samples from patients with partial defects of androgen action. In the current study, we have modified this method to examine AR function in three groups of patients with known or suspected defects of AR function: patients with Reifenstein syndrome, patients with spinobulbar muscular atrophy, and patients with severe forms of isolated hypospadias. When assayed using this method, the AR function of patients with Reifenstein syndrome was intermediate between that of normal control subjects and that of patients with complete testicular feminization. Using the parameters established by the aforementioned experiments, we found that defective AR function can be detected in fibroblasts established from patients with spinobulbar muscular atrophy and in some patients with severe forms of isolated hypospadias, including two with a normal AR gene sequence. These results suggest that this method may have some utility in screening samples to detect defects of AR function, particularly when viewed in the context of other AR assays results.

A novel substitution (Leu707Arg) in exon 4 of the androgen receptor gene causes complete androgen resistance.

A wide spectrum of androgen receptor (AR) gene mutations has been reported in complete androgen insensitivity syndromes. The molecular basis of androgen resistance was investigated in a female newborn with complete testicular feminization. Sequencing identified a point mutation in exon 4 responsible for a leucine (CTG) to arginine (CGG) replacement at codon 707. This novel mutation is located in the amino-terminal part of the ligand-binding domain of the AR. To determine the functional properties of the mutated AR and to establish the correlation with the clinical phenotype of androgen resistance, the mutation was reproduced in AR wild-type complementary DNA, and the plasmid was transfected into AR-free mammalian cells. In vitro studies showed that the mutant AR was functionally defective as an androgen-binding molecule. Electrophoretic mobility shift assay revealed that the binding of mutated AR to DNA was reduced. Finally, the mutant was unable to induce the transcriptional activation of androgen-responsive reporter gene. This amino acid defect in the primary sequence probably involves the rupture of hydropathicity in a region that is conserved among members of the steroid receptor subfamily. Our data substantiate the major contribution of leucine 707 to normal AR function and demonstrate that its substitution by an arginine caused the complete androgen insensitivity in this patient. Our findings also contribute to the elaboration of the structure-function map of the AR based on naturally occurring mutations.

Male Pseudohermaphroditism in the Bowhead Whale, Balaena mysticetus

Examination of two bowhead whales, Balaena mysticetus , revealed an unusual assembly of reproductive structures. Although the external phenotype was female, the gonads were underdeveloped testes. In the more thoroughly studied of the two whales, all derivatives of the mesonephric (wolffian) and paramesonephric (mullerian) ducts were absent, and there was an apparently normal male karyotype (40 autosomes + XY). These findings suggest a failure of androgen expression consistent with the syndrome of complete testicular feminization reported in other species. Structural comparisons with two normal male bowheads confirm abnormal development in the two affected whales.

Amino acid substitutions in the hormone-binding domain of the human androgen receptor alter the stability of the hormone receptor complex.

We have investigated the basis of androgen resistance in seven unrelated individuals with complete testicular feminization or Reifenstein syndrome caused by single amino acid substitutions in the hormone-binding domain of the androgen receptor. Monolayer-binding assays of cultured genital skin fibroblasts demonstrated absent ligand binding, qualitative abnormalities of androgen binding, or a decreased amount of qualitatively normal receptor. The consequences of these mutations were examined by introducing the mutations by site-directed mutagenesis into the androgen receptor cDNA sequence and expressing the mutant cDNAs in mammalian cells. The effects of the amino acid substitutions on the binding of different androgens and on the capacity of the ligand-bound receptors to activate a reporter gene were investigated. Substantial differences were found in the responses of the mutant androgen receptors to incubation with testosterone, 5 alpha-dihydrotestosterone, and mibolerone. In several instances, increased doses of hormone or increased frequency of hormone addition to the incubation medium resulted in normal or near normal activation of a reporter gene by cells expressing the mutant androgen receptors. These studies suggest that the stability of the hormone receptor complex is a major determinant of receptor function in vivo.

Laparoscopic Gonadectomy in Two Patients with Complete Androgen Insensitivity Syndrome

ABSTRACT Patients with Morris syndrome are genetic males with female phenotype who have a 25% chance of developing a malignancy in the dysgenetic gonad. Gonadectomy at laparotomy has always been the elective procedure in patients with complete testicular feminization. We performed the same intervention at laparoscopy in 2 patients. A shorter operating time and less postoperative care are required, the risk of infective complications is lower, and psychologic stress is less. (J GYNECOL SURG 10:259, 1994)

The adenovirus-mediated delivery of a reporter gene permits the assessment of androgen receptor function in genital skin fibroblast cultures. Stimulation of Gs and inhibition of G(o).

Defects in the androgen receptor cause a spectrum of abnormalities in genetic males ranging from phenotypic women with testicular feminization to men with minor defects in fertility and/or virilization. The diagnosis of androgen resistance can be quite cumbersome, including analysis of the family history, karyotyping, endocrine studies, measurement of androgen binding in genital skin fibroblasts, and, in some instances, sequencing of mutant cDNAs. Furthermore, androgen-binding studies may be normal in patients with qualitative receptor abnormalities or mutations in the DNA-binding domain of the receptor. To circumvent these difficulties, we have used a recombinant adenovirus to deliver an androgen-responsive reporter gene (mouse mammary tumor virus-luciferase) to fibroblasts cultured from genital skin from 12 normal controls and from eight individuals with complete testicular feminization. Following incubation with androgen (2 nM mibolerone) for 72 h, luciferase activity in normal fibroblasts increased > 10-fold (range 11-200-fold) in a manner that corresponded with the level of androgen receptor detected in ligand-binding assays. By contrast, luciferase activity increased negligibly in fibroblasts from individuals with testicular feminization (average = 1.2-fold increase). This assay permits a direct assessment of endogenous androgen receptor function in cells and should be a powerful aid in the diagnosis of androgen resistance.

Psychosexual functioning in women with complete testicular feminization: is androgen replacement therapy preferable to estrogen?

Effects of oral testosterone undecanoate (Andriol) on blood hormone levels, moods, sociosexual functioning and self-image of the body were studied in four gonadectomized patients with complete testicular feminization. In a double-blind cross-over experiment, patients were treated with oral testosterone undecanoate (120 mg/day) or placebo for four weeks. Peripheral blood was taken for hormone assays at the end of each four-week period. Psychosexual functioning was reported once weekly, mood scales twice weekly. In three patients testosterone treatment resulted in adult male blood levels of testosterone and estradiol. One patient did not show increased steroid levels, possibly because of hyperthyroxinaemia. No systematic effects were found on coitus, masturbation, sexual thoughts, scores on desire for bodily contact, and on attention for physical appearance. In one patient there was a marked and sustained rise in the positive moods and a fall in negative moods during androgen treatment. These results do not demonstrate that androgen therapy is preferable to estrogen in gonadectomized women with complete testicular feminization with regard to psychosexual functioning.

Laparoscopic gonadectomy in a case of testicular feminization

Laparoscopy provides a minimally invasive technique for the accurate diagnosis of intersex problems and may also provide the opportunity for therapeutic management of these patients. Herein, we report our management of a patient with complete testicular feminization, by laparoscopic bilateral gonadectomy of fully developed intra-abdominal testes.

Complete testicular feminization caused by an amino-terminal truncation of the androgen receptor with downstream initiation.

We have characterized the molecular defect causing androgen resistance in two 46,XY siblings with complete testicular feminization. Although binding studies in genital skin fibroblasts showed a reduced Bmax, an increased dissociation rate of ligand, and an 8S peak of dihydrotestosterone binding on sucrose density gradient centrifugation, no immunoreactive androgen receptor (AR) was detected in immunoblots using anti-NH2-terminal antibodies, suggesting an abnormal amino terminus. Sequence analysis of the AR gene revealed a point mutation CAG-->TAG (Gln-->Stop) at nucleotide 340. In vitro mutagenesis studies suggest the synthesis of the mutant AR is initiated downstream of the termination codon at reduced levels and that each molecule is functionally impaired. These results define a novel mechanism causing androgen resistance: the combination of decreased amount and functional impairment of AR caused by an abnormality within the amino terminus of the receptor. These findings suggest that domains important to the in vivo function of the receptor reside within the amino terminus and that disruption of these domains can occur with only subtle effects on receptor binding. Identification of this mutation made it possible to identify the mutant allele within the family and to ascertain antenatally that it was not present in a 46,XY fetal sibling of the proband at 9 wk gestation.

Genetic basis of endocrine disease. 4. The spectrum of mutations in the androgen receptor gene that causes androgen resistance.

Mutations in the androgen receptor gene cause phenotypic abnormalities of male sexual development that range from a female phenotype (complete testicular feminization) to that of undervirilized or infertile men. Using the tools of molecular biology, we have analyzed androgen receptor gene mutations in 31 unrelated subjects with androgen resistance syndromes. Most of the defects are due to nucleotide changes that cause premature termination codons or single amino acid substitutions within the open reading frame encoding the androgen receptor, and the majority of these substitutions are localized in three regions of the androgen receptor: the DNA-binding domain and two segments of the androgen-binding domain. Less frequently, partial or complete gene deletions have been identified. Functional studies and immunoblot assays of the androgen receptors in patients with androgen resistance indicate that in most cases the phenotypic abnormalities are the result of impairment of receptor function or decreases in receptor abundance or both.

Immunoreactive androgen receptor expression in subjects with androgen resistance.

Individuals with androgen resistance encompass a spectrum of phenotypic abnormalities ranging from complete testicular feminization to undervirilized men. Such subjects have been classified according to the hormone-binding characteristics in genital skin fibroblasts and on the basis of the mutation in the androgen receptor (AR) gene. Antibodies to the amino-terminal region of the human AR were used to develop an immunoblot assay for the comparison of androgen binding with the amount of AR expressed in genital skin fibroblasts. In controls and 4 androgen-resistant subjects with DNA-binding domain mutations, levels of immunoreactive AR correlated closely with androgen-binding capacity. In 15 androgen-resistant subjects with qualitatively abnormal AR, immunoreactive AR levels tended to be higher than predicted from the ligand-binding capacity. Discordance between immunoreactivity and androgen binding also occurred in fibroblasts from 3 other subjects. One carries a stop codon in the AR gene and produces a truncated AR that is immunoreactive but does not bind androgen. Two carry single point mutations in the hormone-binding domain and produce immunoreactive AR that is normal in size but does not bind androgen.

Mutations in the ligand-binding domain of the androgen receptor gene cluster in two regions of the gene.

We have analyzed the nucleotide sequence of the androgen receptor from 22 unrelated subjects with substitution mutations of the hormone-binding domain. Eleven had the phenotype of complete testicular feminization, four had incomplete testicular feminization, and seven had Reifenstein syndrome. The underlying functional defect in cultured skin fibroblasts included individuals with absent, qualitative, or quantitative defects in ligand binding. 19 of the 21 substitution mutations (90%) cluster in two regions that account for approximately 35% of the hormone-binding domain, namely, between amino acids 726 and 772 and between amino acids 826 and 864. The fact that one of these regions is homologous to a region of the human thyroid hormone receptor (hTR-beta) which is a known cluster site for mutations that cause thyroid hormone resistance implies that this localization of mutations is not a coincidence. These regions of the androgen receptor may be of particular importance for the formation and function of the hormone-receptor complex.