Pituitary-gonadal axis in male undermasculinisation.

AIMS: To study the value of assessing serum concentrations of luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone, and dihydrotestosterone (DHT) in patients with male undermasculinisation not caused by androgen insensitivity. METHODS: A retrospective study of a register of cases of male undermasculinisation (20 with abnormal testes, eight with 5alpha-reductase deficiency, three with testosterone biosynthetic defects, seven with Drash syndrome, and 210 undiagnosed). RESULTS: A human chorionic gonadotropin (hCG) stimulation test was performed in 66 of 185 children with male undermasculinisation. In 41 of 66 patients the dose of hCG was either 1000 U or 1500 U on three consecutive days. The rise in testosterone was related to basal serum testosterone and was not significantly different between the two groups. Testosterone:DHT ratio in patients with 5alpha-reductase deficiency was 12.5-72.8. During early infancy, baseline concentrations of LH and FSH were often within normal reference ranges. In patients with abnormal testes, median pre-LHRH (luteinising hormone releasing hormone) concentrations of LH and FSH were 2 and 6.4 U/l, respectively, and post-LHRH concentrations were 21 and 28 U/l. An exaggerated response to LHRH stimulation was observed during mid-childhood in children where the diagnosis was not clear and in all children with abnormal testes. CONCLUSIONS: The testosterone:DHT ratio following hCG stimulation is more reliable than the basal testosterone:DHT ratio in identifying 5alpha-reductase deficiency. During infancy, the LHRH stimulation test may be more reliable in identifying cases of male undermasculinisation due to abnormal testes than basal gonadotrophin concentrations.     

Molecular analysis of the AR and SRD5A2 genes in patients with 46,XY disorders of sex development

The aim of this study was to assess the clinical and endocrinological features, and to analyze AR and SRD5A2 genes in patients with 46,XY disorders of sex development (DSD). This study included 20 patients from 19 families showing clinical features of 46,XY DSD. Molecular analysis was performed of the AR and SRD5A2 genes, as well as endocrinological evaluations, such as 17a-hydroxyprogesterone, plasma renin activity, aldosterone, adrenocorticotropic hormone and hCG stimulation test. Out of 20 patients with 46,XY DSD, only one (5%) displayed androgen insensitivity syndrome (AIS), and four (20%) were 5alpha-reductase deficient by mutation analysis. The patient with AIS revealed significant elevation of serum testosterone following hCG stimulation. The patient with 5alpha-reductase deficiency with a homozygous p.R246Q mutation had a low basal dihydrotestosterone level. The patient with p.Q6X/p.R246Q mutations showed a moderately elevated testosterone/dihydrotestosterone ratio following hCG stimulation. Endocrinological tests are not reliable for the etiological diagnosis of AIS and 5alpha-reductase deficiency due to variable reference ranges of hormonal profiles according to the age and the severity of the enzyme defect. DNA analysis may be employed as a tool for the early and precise diagnosis of patients with 46,XY DSD, and genetic counseling can be used for families at risk.     

Pituitary-gonadal axis in male undermasculinisation

AIMS—To study the value of assessing serum concentrations of luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone, and dihydrotestosterone (DHT) in patients with male undermasculinisation not caused by androgen insensitivity.
METHODS—A retrospective study of a register of cases of male undermasculinisation (20 with abnormal testes, eight with 5α-reductase deficiency, three with testosterone biosynthetic defects, seven with Drash syndrome, and 210undiagnosed).
RESULTS—A human chorionic gonadotropin (hCG) stimulation test was performed in 66 of 185 children with male undermasculinisation. In 41 of 66 patients the dose of hCG was either 1000 U or 1500U on three consecutive days. The rise in testosterone was related to basal serum testosterone and was not significantly different between the two groups. Testosterone:DHT ratio in patients with 5α-reductase deficiency was 12.5-72.8. During early infancy, baseline concentrations of LH and FSH were often within normal reference ranges. In patients with abnormal testes, median pre-LHRH (luteinising hormone releasing hormone) concentrations of LH and FSH were 2and 6.4 U/l, respectively, and post-LHRH concentrations were 21and 28 U/l. An exaggerated response to LHRH stimulation was observed during mid-childhood in children where the diagnosis was not clear and in all children with abnormal testes.
CONCLUSIONS—The testosterone:DHT ratio following hCG stimulation is more reliable than the basal testosterone:DHT ratio in identifying 5α-reductase deficiency. During infancy, the LHRH stimulation test may be more reliable in identifying cases of male undermasculinisation due to abnormal testes than basal gonadotrophin concentrations.
     

Diagnosis of 5alpha-reductase type 2 deficiency: contribution of anti-Müllerian hormone evaluation

AIM: To evaluate anti-Müllerian hormone (AMH) levels in patients with clinical and molecular diagnosis of 5alpha-reductase 2 deficiency. PATIENTS AND METHODS: Data from 14 patients whose age ranged from 21 days to 29 years were analyzed according to age and pubertal stage. Sexual ambiguity was rated as Prader III in 11 patients. LH, FSH, testosterone (T), dihydrotestosterone (DHT) and AMH serum levels were measured in all but two patients, who had been previously submitted to gonadectomy; T and DHT were also measured in 20 age-matched controls. RESULTS: Gonadotropin levels were normal in all but one patient who retained gonads (six of whom had reached puberty) and T/DHT ratio was elevated in all patients when compared to controls. All prepubertal patients had AMH levels < -1 SD for age, while most pubertal patients had AMH levels compatible with pubertal stage. CONCLUSIONS: Prepubertal patients with 5alpha-reductase 2 deficiency have AMH values in the lower part of the normal range. These data indicate that T does not need to be converted to DHT to inhibit AMH secretion by Sertoli cells.     

Choice of gender in 5alpha-reductase deficiency: a moving target

Steroid 5alpha-reductase deficiency is a rare, male-limited autosomal recessive disorder caused by mutation in the SRD5A2 gene resulting in a deficiency of dihydrotestosterone (DHT) during fetal development. Here we report an affected 46,XY adolescent who was born with incompletely virilized genitalia and was raised in the female gender. At 12 years of age, the patient requested feminizing genital surgery. Surgery was withheld and psychiatric counseling was instituted. At 14 years of age, the patient's gender identity and role appeared to be in transition from a female to an increasingly male gender. This case demonstrates that in patients with disorders such as 5alpha-reductase deficiency, in which significant prenatal androgen exposures are combined with postnatal virilization, adult gender identity and gender role may be a dynamic process that is not complete until well after adolescence.     

A novel mutation of the 5alpha-reductase type 2 gene in two unrelated Egyptian children with ambiguous genitalia

OBJECTIVE: To establish an etiological diagnosis in two unrelated Egyptian children with ambiguous genitalia through biochemical and molecular analyses. PATIENTS AND METHODs: Two XY patients were referred: one at the age of 14 years presenting with delayed puberty and menarche and the second at the age of 4 months with ambiguous genitalia. Basal and post-HCG stimulation plasma levels of testosterone (T) and dihydrotestosterone (DHT) were determined. Direct sequencing of the five exons of the 5alphaR type 2 gene and exons 2 to 8 of the androgen receptor gene was carried out. RESULTS: The high T/DHT value indicated 5alphaR deficiency in the first patient while the absence of parental consanguinity along with normal T/DHT value in the second patient suggested androgen insensitivity. In both patients, we identified a homozygous A --> G mutation in exon 3 that replaced the asparagine residue at position 160 by an aspartic acid. The parents of both patients were all heterozygotes for the N160D substitution. CONCLUSIONS: 1) We report a new mutation that enlarges the spectrum of genetic defects in 5alphaR deficiency. 2) Although the two patients were referred at very different ages, the clinical presentations raise the possibility of phenotypic variability for the same mutation. 3) These reports underline the difficulty of diagnosing 5alphaR deficiency based only on clinical and biochemical grounds. Molecular study remains the only definitive tool for diagnosis of ambiguous genitalia.     

5alpha-reductase 2 gene mutations in three unrelated patients of Greek Cypriot origin: identification of an ancestral founder effect

INTRODUCTION: 5alpha-Steroid reductase deficiency (5alphaSRD) is an autosomal recessive enzymatic deficiency. Mutations in the 5alpha-steroid reductase type 2 gene (SRD5A2) result in male pseudohermaphroditism caused by decreased dihydrotestosterone (DHT) synthesis--a key hormone of virilization of male external genitalia. AIM: To study for the first time patients from the Greek Cypriot population, describe their clinical characteristics, and identify the genetic mutations of the SRD5A2 gene. PATIENTS AND METHODS: Three unrelated patients with 46,XY karyotype born with ambiguous genitalia were examined. Patient 1 was raised as a girl and was diagnosed with partial androgen insensitivity syndrome, based on the clinical picture and incomplete laboratory investigation at the age of 4 years, and underwent gonadectomy. For this patient sequencing analysis of all five exons of the SRD5A2 gene and exons 2 to 8 of the androgen receptor (AR) gene was performed. Patients 2 and 3 were also born with ambiguous genitalia. The hCG test for these two patients was informative of 5alphaSRD, as it showed elevated T/DHT ratio after stimulation. Despite genetic counseling, both families decided to raise their infants as females because of severe under-virilization. Sequencing of the SRD5A2 gene was also completed for both patients. RESULTS: No mutations were found in the AR sequence for patient 1. Patients 1 and 3 were found homozygous for the mutation A/G at splice junction intron 1/exon 2 and patient 2 was found heterozygous for the same A/G substitution and also heterozygous for an additional mutation, Pro181Leu, in exon 3. CONCLUSIONS: The same mutation in the SRD5A2 gene was identified in three unrelated patients, in both homozygous and heterozygous form. This splice mutation was previously reported in Turkish patients. This underlying genetic abnormality may be characteristic for the Eastern Mediterranean region and is likely due to an ancestor effect.     

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.     

Smith-Lemli-Opitz syndrome: in vivo and in vitro study of testicular function in a prepubertal patient with ambiguous genitalia

The pathogenesis of the development of ambiguous genitalia reported in some 46,XY patients with Smith-Lemli-Opitz syndrome is not understood. Presumably, it is related to the 7-dehydrocholesterol reductase deficiency present in these patients. In this study we have evaluated testicular function, both in vivo and in vitro, in a 46,XY patient with ambiguous genitalia, reared as a girl. The diagnosis was based on clinical features, low serum cholesterol and high serum 7-dehydrocholesterol levels. Serum hormone values, determined during the first month of age, showed normal basal testosterone (1.95 ng/ml), LH (0.91 U/l) and FSH (2.51 U/l). However, serum testosterone did not increase after hCG administration (1.98 ng/ml). On the other hand, the patient had a positive biological response to exogenous testosterone (decrease in sex hormone-binding globulin serum levels). She was orchidectomized at the age of 33 mo. Testicular cells were dispersed and maintained in culture for 6 d. These cells showed a very good capacity to secrete testosterone into the culture medium (X +/- SD, 26.1 +/- 11.7 vs. 4.36 +/- 1.70 pmol/10(6) cells/24 h in a control group of testicular cells prepared from testes collected at necropsy). The patient's cells failed to respond to LH stimulation (18.6 +/- 4.0 pmol/10(6) cells/24 h), although they did respond to other stimuli. It is concluded that the severe cholesterol deficiency of this patient did not impair the capacity of the testes to synthesize testosterone. However, the LH/hCG receptor or its subsequent message was activated neither in vivo nor in vitro. This finding suggests that the foetal testes might have failed to respond to placental hCG at the time of male external genital differentiation. This failure could have been responsible for the ambiguous genitalia present in this patient.     

Incomplete androgen insensitivity syndrome. Difficulties of diagnosis and management

A familial form of incomplete androgen insensitivity syndrome (AIS) is reported. The index case was first seen at 9 months of age for ambiguous genitalia. Diagnosis of AIS, suspected but first discarded on the basis of an androgen sensitivity test, was finally made at puberty on the discordance between poor virilization and elevated levels of both testosterone and LH, a florid gynecomastia, and the exclusion of any enzymatic defect in testosterone biosynthesis of 5 alpha-reductase deficiency. Androgen receptors in public skin were within the limits of normal for total number, with normal affinity. Familial occurrence included 2 first cousins born 7 and 10 years later, a maternal grand-uncle with similar ambiguous genitalia, and a maternal uncle with the gynecomastia-preserved fertility syndrome. This case report illustrates the heterogeneity of AIS in a given family and the difficulty of and early positive diagnosis in a newborn presenting with sexual ambiguity.     

5α-还原酶2缺乏症5例临床表型与基因型分析

目的探讨5α-还原酶2缺乏症的临床表型与基因型特点。方法回顾分析5例5α-还原酶2缺乏症患儿的临床资料,分析临床表型与基因型之间的关联性。结果 5例患儿都表现为阴茎短小(3例类似阴蒂外观),睾丸发育不良。5例患儿人绒毛膜促性腺激素(h CG)激发后睾酮/双氢睾酮(T/DHT)比值10.26~64.99。基因检测显示,1例为纯合突变c.680 GA,4例为复合杂合突变;突变性质主要为错义变异,其次分别为缺失、重复、无义变异。结论 5α-还原酶2缺乏症的临床表型均有外生殖器发育异常,基因检测有助于疾病的诊断。     

Familial male pseudohermaphroditism

Familial male pseudohermaphroditism (MPH) due to 17, 20-desmolase deficiency is rare. Here we present two siblings with MPH possibly due to 17, 20-desmolase deficiency. The first patient presented with unambiguous female external genitalia and hypergonadotrophic hypogonadism. Chromosomal analysis revealed 46 XY. Ultrasound evaluation of pelvis revealed gonads in the inguinal canal, and no uterus. These findings were confirmed on laparotomy. Histology revealed the gonads to be testes. The second patient had ambiguous genitalia (perineoscrotal hypospadias, bifid scrotum with palpable gonads) with a 46 XY chromosomal pattern. Both patients had high plasma 17-hydroxy progestrone (17 OHP), low normal dehydro epiandrosterone sulphate (DHEAS) and low plasma testosterone. Plasma testosterone and DHEAS showed no response to ACTH or HCG. These features are compatible with the diagnosis of 17, 20-desmolase deficiency.     

The testicular lesion and sexual differentiation in congenital lipoid adrenal hyperplasia

Congenital lipoid adrenal hyperplasia results in deficient virilization of genetic male infants, indicating that gonadal testosterone biosynthesis is impaired in such patients. In order to better define the characteristics of the gonadal lesion, we studied a Japanese genetic male infant with congenital lipoid adrenal hyperplasia who underwent bilateral orchiectomy at 14 months of age. The basal serum testosterone was low before and after orchiectomy (6.6 +/- 1.1 vs. 9.5 +/- 1.3 ng/dl), though it was higher at 9 days of age (30 ng/dl). A stimulation test with human chorionic gonadotropin at 12 months of age yielded no testosterone response (7----less than 5 ng/dl). At the time of the surgical intervention, the external genitalia were completely female but Wolffian duct derivatives (epididymides and vasa deferentia) were well developed. The microscopic examination of the testes revealed an increased number of Leydig cells which were filled with abundant lipoid material.- The above data demonstrate that the fetus produced a sufficient amount of testicular testosterone for a male Wolffian duct development. This indicates a quantitative difference in androgen requirements for the male sexual development of the external genitalia and the Wolffian ducts.     

Practical approach to steroid 5alpha-reductase type 2 deficiency

The aim of this article is to review the literature on steroid 5alpha-reductase type 2 deficiency (5α-RD2) to provide clinicians with information to guide their management of patients with this disorder. The 5alpha-reductase type 2 is encoded by the 5alpha-reductase type 2 gene (SRD5A2) on chromosome 2 and is predominantly expressed in external genital tissues and the prostate. Mutations of the SRD5A2 gene leads to an uncommon autosomal recessive disorder affecting sexual differentiation in individuals with 46,XY karyotype; their phenotype can range from almost normal female structures to a distinct male phenotype with ambiguous genitalia at birth. These phenotypes result from impaired conversion of testosterone to dihydrotestosterone due to mutations in the SRD5A2 gene. Patients exhibit virilization at puberty without breast development, which is often accompanied by gender identity change from female to male. More than 40 mutations have been reported in all five exons of the SRD5A2 gene. Phenotype–genotype correlations for 5α-RD2 have not been well established. The newborn phenotypes of male pseudohermaphrodites with 5α-RD2, partial androgen insensitivity syndrome (PAIS), or 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) enzyme deficiency may be indistinguishable. We conclude that steroid 5α-RD2 should be included in the differential diagnosis of newborns with 46,XY DSD. It is important that the diagnosis be made in infancy by biochemical and molecular studies before gender assignment or any surgical intervention because these patients should be considered males at birth.     

Hyperphenylalaniaemia due to dihydropteridine reductase deficiency

Two siblings with increased levels of serum phenylalanine were detected by newborn screening. The older sibling deteriorated neurologically and mentally, despite early dietary control, and died at the age of 6 1/2 years. In the younger sibling phenylalanine hydroxylase activity in liver tissue was normal. Further investigations revealed increased concentrations of biopterin derivatives in the blood, a low excretion of 5-hydroxyindole acetic acid in the urine, and a dihydropteridine reductase deficiency as the cause of hyperphenylalaninaemia. The parents of the siblings showed 50% of the normal dihydropteridine reductase activity in their fibroblasts grown in culture. Neurotransmitter therapy was started in the second child at the age of 6 months and this was followed by distinct neurological and mental improvement.Dedicated to Prof. Dr.H. Bickel on occasion of his 60th birthday     

Male pseudohermaphroditism due to 5α-reductase deficiency in a Swedish family

Three sibs with an inherited form of male pseudohermaphroditism are described. They were all born with ambiguous external genitalia but no diagnosis of a possible enzyme defect was made during childhood. First seen at the ages of 16, 14 and 10 years respectively, they were investigated in order to establish the pathogenetic nature of the disorder. Serum concentrations of testosterone and dihydrotestosterone before and after stimulation with human chorionic gonadotropin suggested 5-reductase deficiency. Measurement of steroid metabolites in urine confirmed this diagnosis. It is essential to recognize this condition in order to decide the sex of rearing of the children.     

17 beta-hydroxysteroid dehydrogenase 3 deficiency in the Mediterranean population

Eighty-five males with 17 beta-HSD3 were identified among a highly inbred Arab population in Israel and 57 studied over a period of 25 years. The founders of this defect originated in the mountainous regions of present Lebanon and Syria, but most of the families now live in Jerusalem, Hebron, the Tel-Aviv area and, in particular, in Gaza, where the frequency of affected males is estimated at 1 in 100 to 150. Affected individuals are born with ambiguity of the external genitalia and reared as females until puberty. Thereafter marked virilization occurs, leading in many cases to the spontaneous adoption of a male gender identity and role. Adults develop a male habitus with abundant body hair and beard and the phallus and testes enlarge to adult proportions. Gender reassignment in infancy was only possible when enough erectile tissue was present at birth and developed into a normal size penis with testosterone. 17 beta-HSD3 deficiency can be reliably diagnosed by endocrine evaluation and mutation analysis. In adults the defect is characterized by markedly increased concentrations of androstenedione (A) with borderline low to normal testosterone (T) levels and a high A/T ratio. 5a-dihydrotestosterone (DHT) concentrations are moderately decreased, normal or high and dehydroepiandrosterone (DHEA) levels are high. The estrogen pathway is also impaired, even though both estrone (E-1) and estradiol-17 beta (E-2) levels are high. Children have low basal levels of all androgens, but the defect may be demonstrated after prolonged stimulation with human chorionic gonadotropin (HCG). LH and FSH levels are very high after puberty and normal in childhood. 17 beta-HSD3 isozyme is encoded by the chromosome 9q22 17 beta-HSD3 gene and expressed exclusively in testes. A point mutation in exon 3, codon 80 of the 17 beta-HSD3 gene, R80Q, caused by a single base substitution from CGG ( arginine) to CAG ( glutamine) was identified in both alleles of 24 individuals from 9 extended Arab families from Gaza, Jerusalem and Lod-Ramle. Twenty-one homozygote males (46,XY) were MPH with testicular 17 beta-HSD3 deficiency whereas the three homozygote females (46,XX) were asymptomatic, had normal internal and external genitalia, normal sexual development and revealed no biochemical evidence of 17 beta-HSD3 deficiency. The molecular pattern is compatible with an autosomal recessive mode of inheritance, sex dependent.     

Bilateral ovarian steroid cell tumor in congenital adrenal hyperplasia due to classic 11beta-hydroxylase deficiency

An 8.7 year-old patient, raised as a boy, presented with premature appearance of pubic hair and accelerated growth since 2 years of age and ambiguous genitalia noted at birth. There was first degree consanguinity between his parents. A similar problem was reported in a cousin. Examination of the external genitalia revealed complete scrotal fusion, a 5 cm long phallus, urogenital sinus at base of phallus with no gonads palpable. Pigmentation was increased. His blood pressure was 150/100 mm Hg. Pubic and axillary hair were at stage 3. Bone age was 17 years. Adrenal ultrasound was normal. Pelvic ultrasound showed relatively enlarged uterus and ovaries with normal echogenicity. Karyotype was 46,XX. Hormone profile was compatible with congenital adrenal hyperplasia (CAH) due to 11beta-hydroxylase deficiency (11-deoxycortisol: 11.5 nmol/l [400 ng/dl] [normal: 0.6-4.5 nmol/l [20-155 ng/ml]], androstenedione: 17.4 nmol/l [5 ng/ml] [normal: 0.1-1.2 nmol/l [0.03-0.35 ng/ml]]). Prednisolone and antihypertensive drugs were started. The patient underwent bilateral salpingo-oophorectomy and hysterectomy at 9.1 years. Histopathological examination of both ovaries revealed steroid cell tumor. The type of the tumor was "not otherwise specified" (NOS). Basal hormone levels and ACTH test performed 10 months after the operation and 7 days off treatment reconfirmed the diagnosis of 11beta-hydroxylase deficiency. Steroid cell tumors are extremely rare forms of steroid hormone-reducing ovarian neoplasms in childhood and may coexist with or imitate virilizing CAH.     

Familial congenital adrenal hyperplasia caused by 11 beta-hydroxylase. Failure of prevention of sexual ambiguity and prenatal diagnosis

In a sepharad family from Morocco, 2 children out of 4 had congenital adrenal hyperplasia with 11 beta-hydroxylase deficiency. The index case had a very severe genital masculinization (Prader V), diagnosed at 18 months of age. For the fourth pregnancy, dexamethasone was given from the 8th to the 24th week of amenorrhea, in order to prevent the virilization of a female fetus. The treatment was interrupted for 5 days, at the 20th week, because of amniocentesis. As the amniotic steroid concentrations were normal, the treatment was stopped. Nevertheless the neonate also has severe virilization of the external genitalia and postnatal hormonal studies confirmed the diagnosis of congenital adrenal hyperplasia due to 11 beta-hydroxylase deficiency. The reasons for the failure of the treatment are analyzed.     

Molecular genetic analysis and human chorionic gonadotropin stimulation tests in the diagnosis of prepubertal patients with partial 5α-reductase deficiency

Reduced conversion of testosterone (T) to dihydrotestosterone (DHT) results in defective virilization in karyotypic males. Different mutations in the 5-reductase type 2 gene cause the phenotypic variability of the disease. In this report we describe four prepubertal patients with a predominantly male phenotype who carry homozygous point mutations in the 5-reductase type 2 gene and address the specific T and DHT response to different human chorionic gonadotropin (hCG) stimulation tests. For molecular genetic analysis, DNA from peripheral blood leucocytes was studied. The coding region of the 5-reductase type 2 gene was characterized by exon-specific polymerase chain reaction amplification, non-radioactive single strand polymorphism analysis, and direct sequencing. Three different homozygous point mutations (Gly₁₉₆–Ser, Arg₂₂₇–Gln and Ala₂₂₈–Thr) were identified in the patients. In contrast, in the DNA from 100 phenotypically normal males only two heterozygous abnormalities (Ile₁₉₆–Ile, Met₁₅₇) were characterized. For hormonal studies, T and DHT were measured in serum before and after hCG stimulation employing different protocols. HCG stimulation with 5000 IU/m² once and prolonged stimulation with seven injections of 1500 IU hCG per single dose every other day were used.Conclusion While abnormal T/DHT ratios were identified with both hCG protocols in the patients, prolonged stimulation lead to higher T values and to higher T/DHT ratios, and hence to a better discrimination of pathologic results.