MPH due to androgen insensitivity syndrome (AIS) is characterized by 46,XY karyotype, normal testes, normal androgen secretion and impairment in androgen action with consequent impairment of the normal virilization in utero, during and after puberty. AIS is classified as complete form (CAIS) when there is an absolute absence of androgen action and partial form (PAIS) when there are variable degrees of impairment of androgen action. AIS is a classical example of hormone resistance. Mutations in the androgen receptor (AR) gene are responsible for most cases of CAIS and many patients with PAIS. A milder form, mild androgen insensitivity syndrome (MAIS), with male genitalia and micropenis or only infertility has also been described (191). Recently, a patient with a phenotype of CAIS was described with a normal AR gene, but studies in genital skin fibroblasts revealed that transmission of the activation signal by the AF-1 region of the androgen receptor was disrupted, suggesting that a coactivator interacting with the AF-1 region of the AR was lacking in this patient (192).

History: individual patients with probable AIS may have been described as early as 400 AD in the Talmud. In 1950, Lawson Wilkins described a "hairless woman with testes" that failed to respond to testosterone administration (191). Androgens and estrogen biosynthesis was eliminated by gonadectomy and Wilkins postulated insensitivity to androgens as the cause of this disease. In 1953, Morris in 1953 (193) reviewed several patients from the literature and 2 of his own and reported the first comprehensive description of the clinical characteristics of the disorder that he defined as testicular feminization: female habitus, normal female breasts, absent or scanty axillary and pubic hair, female external genitalia with a blind ending vagina, absence or rudimentary internal ducts, and intraabdominal or inguinal gonads. The gonads contained seminiferous tubules usually without spermatogenesis and marked increase in interstitial cells. Gonadotropins were elevated and hormone assays suggested that the testes produced both estrogen and androgen. Some patients originally described as CAIS by Morris might have had other forms of male pseudohermaphroditism.Since these patients have a female social sex, presently, the terminology testicular feminization should be avoided in favor of complete AIS.

Genetic studies: A familial nature of AIS compatible with X-linked recessive inheritance was noted. Rodent models of AIS, termed the testicular feminization (Tfm) mouse and Tfm rat, with androgen resistance were described and the X-chromosome localization of the Tfm locus was established.

In 1974, Keenan et al. (194) demonstrated an absence of androgen binding by the intracellular androgen receptor in cultures of skin fibroblasts from patients with CAIS. Subsequently, decreased binding or qualitative abnormalities of ligand binding were demonstrated in some patients.

The human AR complementary DNA was cloned in 1988 and the AR gene located at the long arm of the X chromosome at Xq11-13, later was refined to Xq11-12. Brown et al. (195) Subsequently, several abnormalities of the AR were reported and are listed in a database found in the web at http://www.mcgill.ca/androgendb/. Additional information on androgen receptor physiology and mutations is available at the section on Male Reproductive Endocrinology: Chapter 3 ANDROGEN PHYSIOLOGY: RECEPTOR AND METABOLIC DISORDERS Albert O. Brinkmann, Ph.D. http://www.endotext.org/male/male3/maleframe3.htm

A partial form of AIS was suggested as the cause of male pseudohermaphroditism in patients with partial androgen resistance. The clinical picture of CAIS is quite homogeneous, while that of partial androgen insensitivity syndrome (PAIS) is very variable. Diagnostic confusion with other causes of male pseudohermaphroditism is more likely. Patients with PAIS have ambiguous genitalia, ranging from predominantly female genitalia with mild clitoromegaly to predominantly male genitalia with micropenis, hypospadias, and development of gynecomastia at puberty. These patients have a 46,XY karyotype, normal testes, and normal testosterone production. When ligand-binding studies demonstrate a diminished or abnormal receptor, a diagnosis of AIS is inferred. Definitive proof of AIS can be obtained when a mutation in the AR gene is demonstrated.

Phenotype: Patients with CAIS have female external genitalia. Discordance between the 46,XY karyotype on amniocentesis and female genitalia on prenatal ultrasound, if performed, may alert the physician. Inguinal hernia may indicate the presence of inguinal testes. At puberty, patients with CAIS have complete breast development and primary amenorrhea. Pubic and axillary regions remain covered with vellous hair only, or very sparse and thin pubic hair. The observation of spontaneous growth acceleration at the time of puberty in patients with CAIS and intact testes who are therefore insensitive to androgens, led Zachmann et al. to conclude the importance of estrogens in the pubertal growth spurt (196). Adult height has been intermediate between that of males and females.

Diagnosis: In a patient with the phenotype described above, after the age of puberty, hormonal diagnosis is performed by the demonstration of normal or elevated serum testosterone levels and slightly elevated LH levels. FSH levels are slightly elevated due to high testicular position or normal. Testosterone precursors are not elevated in relation to testosterone levels (197). DHT levels might be low, resulting in a slightly elevated testosterone/DHT ratio; this has been attributed to a secondary 5-alpha reductase deficiency. It has been suggested that 5 alpha -reductase activity is induced by androgens and that in the absence of androgen action the activity of this enzyme would also be reduced (198). This elevated testosterone/DHT ratio is not a diagnostic problem because patients with 5- alpha reductase type 2 deficiency have ambiguous genitalia. Testicular biopsy shows Leydig cell hyperplasia and relatively normal seminiferous tubules.

In pre pubertal patients, an hCG stimulation test is necessary. After hCG, there is a normal male testosterone response without disproportionate increase of testosterone precursors.

Genetic studies: CAIS has an X-linked recessive pattern of inheritance. Accordingly, the AR gene is located in the X chromosome and hemizygous deletions, frameshift and missense mutations in the AR gene were reported in patients with CAIS (199).

Gender identity/role behavior: Patients with CAIS are raised as girls and have a female gender identity and role behavior (161, 197, 200).

Treatment: Gonadectomy should be performed because of the increased risk of testicular tumors, especially after puberty. About half of pediatric endocrinologists favor waiting for spontaneous feminization during puberty to perform the gonadectomy and start estrogen replacement. We, however, favor prepubertal gonadectomy, after diagnosis, and then induction of puberty with estrogens at the appropriate age. This approach diminishes the time that the girl has an inguinal mass and surgery is better handled psychologically by the young child than the adolescent. Female relatives on the maternal side of the patient can be studied for the mutation of an index case, and if the carrier status is identified genetic counseling should be performed. The risk of having an affected son by a mother carrying the mutated gene is 25%. To date, all patients with CAIS (with the same mutation) in a family have the same phenotype.

Patients with PAIS have a broad spectrum of impairment in virilization.

Phenotype: The external genitalia can vary from predominantly female with clitoromegaly and labial fusion, to predominantly male with micropenis, hypospadias and gynecomastia. Testes are in the inguinal canal or labioscrotal folds or, less frequently, intraabdominal. In our experience, ultrasound has not been superior to careful palpation on physical examination to identify testes when these are located in the inguinal canal or labioscrotal folds (197).

Diagnosis: The clinical diagnosis of PAIS is less straightforward than that of CAIS because the phenotype is more variable. Patients with PAIS have ambiguous genitalia; testes are usually palpable in the inguinal canal or labioscrotal folds. In children, the testosterone response to hCG is normal without accumulation of testosterone precursors. At puberty, partial virilization and gynecomastia develop.

Serum LH levels are in the upper normal range or slightly elevated and testosterone levels are normal or also slightly elevated. Testosterone precursors are not increased in relation to testosterone. The testosterone/DHT ratio is not as high as in patients with 5 alpha-reductase type 2 deficiency or CAIS, but may be slightly higher than the normal population due to a secondary 5 alpha -reductase 2 deficiency (see CAIS Diagnosis). Studies of androgen binding to cultured skin fibroblasts of patients with PAIS have shown diminished binding or qualitative abnormalities of the androgen-receptor interaction. A definitive molecular diagnosis of PAIS is established by the identification of mutations in the AR gene of patients with PAIS.

The diagnosis of PAIS has been attributed to several patients with male pseudohermaphroditism with normal testosterone levels but without identification of mutations in the AR and without definitive proof of androgen resistance. This has led to an overestimation of this diagnosis. We prefer to classify these patients without diagnosis as idiopathic male pseudohermaphroditism until a definitive etiology is established. A timing defect leading to lack of testosterone secretion at the critical period in which the virilization of the genitalia occurs can cause male pseudohermaphroditism, however, this is impossible to determine later in postnatal life with the methods available today.

Genetic studies: The pattern of inheritance is X-linked recessive. Mutations in the AR have been identified in patients with PAIS and the nature of the substitution, the conservation of the amino acid substituted and in vitro studies have explained the alteration of phenotype (191). Screening of relatives, prenatal studies and genetic counseling is performed as in CAIS (see above). In contrast to CAIS, however, patients with PAIS in the same family and with the same mutation have had different degrees of virilization.

Treatment: Unlike CAIS, patients with PAIS are raised as boys or girls. Both need genital reconstruction for feminization or masculinization, according to the assigned sex. In addition, gonadectomy and induction of puberty with estrogens is required in PAIS raised as girls. Progesterone administration is not necessary since these patients do not have a uterus. The medical decision to raise a patient with PAIS is often very difficult. If phallic size is below -2 SD for age, a course of treatment with testosterone or DHT is necessary for treatment and determination of response to androgens. Patients with a very small phallus, without response to androgen treatment, in which the parents are prepared to raise their child as a girl should be assigned the female sex. Patients who have a good response to androgen therapy or when the family will not accept a female sex should be reared as boys. At puberty, gynecomastia can be corrected and high-dose androgen therapy may attempt to obtain a further increase in penile size and body hair. We have given up to 500 mg testosterone esters every 7 days, without side effects but also with variable results.

Smith-Lemli-Opitz syndrome: This syndrome, caused by a deficiency of 7-dehydrocholesterol reductase, is the first true metabolic syndrome leading to multiple congenital malformations (201, 202). This disorder is caused by mutations in the sterol delta-7-reductase (DHCR7) gene, which maps to 11q12-q13. Typical facial appearance is characterized by short nose with anteverted nostrils, blepharoptosis, microcephaly, photosensitivity, mental retardation, syndactly, hypotonia and genital ambiguity. Ambiguity of the external genitalia is a frequent feature of males (71%) and range from hypospadias to female external genitalia despite normal XY karyotype and SRY sequences. Müllerian derivative ducts can also be present (203, 204). The etiology of masculinization failure in the SLO syndrome remains unclear (205).

Affected children present with low plasma cholesterol and elevations of plasma 7-dehydrocholesterol. Considering the relative high frequency of Smith-Lemli-Opitz syndrome, approximately 1 in 20,000 to 60,000 births, we suggest that at least cholesterol levels should be routinely measured in patients with MPH.

Treatment: Dietary cholesterol would supply cholesterol to the tissues and also reduce the levels of 7-dehydrocholesterol. Administration of cholesterol by mouth results in growth of SLOS infants and converts the patient from an irritable, whining individual to a quiet and interactive one (206).

The development of female internal genitalia in a male individual is due to the incapacity of Sertoli cells to synthesize or secrete AMH or to alterations in the hormone receptor. Persistent Müllerian duct syndrome (PMDS) phenotype can be produced by a mutation in the gene encoding anti-Müllerian hormone or by a mutation in the AMH receptor. These two forms result in the same phenotype and are referred to as type I and type II, respectively (207).

AMH is a 145,000 MW glycoprotein homodimer produced by Sertoli cells not only during the period when it is responsible for regression of the Müllerian ducts but also in late pregnancy, after birth, and even, albeit at a much reduced rate, in adulthood (207, 208). The AMH gene is located in chromosome19p.13.3 and it is a small gene containing 5 exons (209). The AMH receptor a serine/threonine kinase is a member of the family of type II receptors for TGF-β-related proteins (210).

Phenotype: these patients present a male phenotype, usually along with bilateral cryptorchidism and inguinal hernia. There are two anatomic forms: in the more prevalent one, the hernia contains the tubes, uterus and testis or the testis can also be on the scrotum; in the second form, both testes, tubes and uterus are in the pelvis (211). Leydig cell function is preserved, but azoospermia is common due to the malformation of ductus deferens or epididymides agenesis. When the hernia is surgically corrected, the presence of a uterus, Fallopian tubes and superior part of the vagina can be verified.

Genetic studies: PMDS is a hetorogeneous disorder that is inherited in a sex-limited autossomal recessive manner. Mutations in AMH gene or AMH receptor gene are the cause of PMDS (212, 213).

Hormonal Diagnosis: Normally, AHM levels are measurable during childhood and decrease at puberty. Patients with AMH gene defects have low AMH levels since birth whereas patients with mutations in AMH receptor gene have elevated AMH levels.

Treatment: is directed toward an attempt to assure fertility in males. Early orchiopecxy, proximal salpingectomy (preserving the epididymides), a complete hysterectomy with dissection of the vas deferens from the lateral walls of the uterus are indicated (214).

It is important to stress that the treatment of male pseudohermaphrodite patients requires an appropriately trained multi-disciplinary team. Early diagnosis is important for good outcome of the patients and should start with a careful examination of the newborn's genitalia at birth (227).

Psychological Evaluation: It is of crucial importance to treat intersex patients. Every couple that has a child with ambiguous genitalia must be assessed and receive counseling by an experienced psychologist. Furthermore, the psychologist must specialize in gender identity (228, 229) .

Parents must be informed by the physician and psychologist about sexual development, emphasizing that until two months of intra-uterus age, both male and female fetuses have the same external and internal genitalia and that sex determination and differentiation depend on several components, one of them being the sex chromosome. A simple, detailed, and comprehensive explanation about what to expect regarding integration in social life, sexual activity, necessity of hormonal and surgical treatment and the possibility, or impossibility of fertility according to the sex of rearing, should also be addressed to the parents, before the definition of the final social sex. In case parents and health care providers disagree over the sex of rearing, the parents' choice must be respected.

For patients older than 5-7 years, the psychological analysis in our center includes free and directed anamnesis. The techniques are designed to evaluate the psychodynamics and the behavioral features of the subjects, including evaluations of the social and sexual attitudes of the patients. The personality HTP (house, tree, person) tests, family and free drawings, and the Form C Pierre Weil and Eva Nick non-verbal intelligence tests and Szoundi tests are applied, and devolutive interviews are conducted with the patients and their parents. After psychological diagnosis, the subjects are followed periodically, more frequently during the periods before and after genitoplasty.

The determination of the social sex must take into account the ethiological diagnosis, penis size, sexual identity and the acceptance of the assigned social sex by the parents. The affected child and his/her family must be followed throughout life to ascertain the patient's adjustment to his/her social sex. Whenever there are signs of inadequate behavior, the patient should be carefully re-evaluated.

Female social sex: The purpose of the hormonal therapy is the development of female sexual characteristics and menses in the patients with uterus. The treatment must simulate a normal puberty, by introducing low doses of conjugate estrogens (0.07 to 0.15 mg/day orally) at 9-11 years to avoid excessive bone maturation. The initial dosage is kept as the patient presents progressive breast development, and is assessed bimonthly. If breast development is not progressive, the estrogen dose is increased up to 1.25 mg/day. After the breast development is complete, the conjugate estrogen dose is maintained at 0.625 mg/day continuously and medroxyprogesterone acetate (5 to 10 mg/day, from the 1st to the 12th day of the month) is added to induce menses. In patients without a uterus only estrogen is indicated.

When the diagnosis is attained after the pubertal age, the therapy should be started with conjugate estrogens 0.625 mg/day for 6 months and then associate progesterone. During hormonal replacement therapy, all female social sex patients must undergo a routine gynecological evaluation once a year. Estrogen and progestagen replacement can also be performed through the use of topic natural or synthetic steroids such as a gel or patch.

Male social sex: Testosterone replacement is started between 10 and 11 yrs, simulating normal puberty according to the child's psychological evaluation and height. The initial dose is 25 to 50 mg/month of testosterone esters IM. The development of secondary sexual characteristics and growth velocity are evaluated every three months and bone age is assessed once a year. The dose is doubled every 6-12 months according to the development of secondary sexual characteristics. The maintenance dose in an adult patient is 200 to 250 mg every 2 weeks. After the testosterone esters injection there is a huge increase in serum testosterone that remains for 24 to 48 hours afterwards (1,500-2,800 ng/dL) with a slow decline that reaches levels at the inferior normal range on the 14th day after the injection (200-300 ng/dL). There are few side effects with the chronic use of testosterone esters. Some patients present transitory inferior edema after the first doses and slight and transitory gynecomastia is present in almost all patients, except in patients with male pseudohermaphroditism due to 5-α-reductase type 2 deficiency.

In male patients with peripheral insensitivity, higher doses of testosterone esters (250-500 mg twice a week) are used to increase penis size and male secondary characteristics. The maximum penis enlargement is obtained after 6 months of high doses and after that, the normal dosage is re-instituted.

The use of topic DHT gel is also useful to increase penis size with the advantage of not causing gynecomastia and of promoting a faster increase of penis size, as DHT is 50 times more active than testosterone. Considering that DHT is not aromatized, one would expect it to have no effect on bone maturation, allowing the use of higher doses than testosterone and consequently a greater amount of virilization.

The aim of the surgical treatment is to correct the external genitalia and remove internal structures that are inadequate to the social sex. Patients must undergo surgical treatment preferably before 2 years of age, which is the time when the child becomes aware of his/her genitals and social sex.

Female social sex patients undergo phalloplasty, keeping the glans clitoris that is implanted in the perineum and opening of the urogenital sinus isolating urethra from vagina with the exposing of the vaginal introitus.

Male social sex patients undergo surgery in two phases with a 6-month interval between them: in the first phase, orthophalloplasty, with removal of the ventral chord, proximal neourethroplasty and colpectomy when necessary and in the second phase distal neourethroplasty, correction of bifid scrotum and cryptorchidism.

Laparoscopy has gained acceptance as the ideal method of surgical treatment of the internal genital organs in patients with intersex disorders (230, 231). In these patients, the indications for laparoscopy are the removal of normal gonads and ductal structures that are contrary to the assigned gender and the removal of dysgenetic gonads that are nonfunctional and that present potential for malignancy. In addition to being a minimally invasive surgery, one of the main advantages of this method is the lack of scars. Generally, gonadectomy is a straightforward operation because the gonads present with an accessible pedicle and laparoscopic orchidopexy can be performed in patients in whom the testis must be relocated to the scrotum (231).

The results of the surgical correction are good, from both the esthetic and functional points of view. Most of our patients report satisfactory sexual performance as long as they present a penis size of at least 6 cm. Patients with female social sex who wish to initiate sexual activity undergo vaginal dilation with acrylic molds of progressive sizes, this results in a functional vagina after 6-10 months of treatment (190).

Infertility is almost always present in male pseudohermaphroditism due to impaired spermatogenesis secondary to gonadal dysgenesis, testosterone deficiency or action, cryptorchidism, or retrograde ejaculation, are frequently found in patients with perineal hypospadias. Currently, the development of in vitro fertilization techniques has enabled male pseudohermaphrodite patients to produce offspring (184, 232)