Congenital disorders of estrogen biosynthesis and action.

Estrogens regulate pubertal development and reproductive function in women, spermatogenesis in men, and bone turnover and metabolic conditions in individuals of both sexes. Estradiol, the major estrogen in humans, is synthesized from testosterone by the action of aromatase and exerts its effects though binding to estrogen receptors. Germline loss- and gain-of-function variants in CYP19A1, the gene encoding aromatase, lead to aromatase deficiency and aromatase excess syndrome, respectively. Germline loss-of-function variants in ESR1, the gene encoding estrogen receptor α, are known to cause of estrogen insensitivity/resistance. In addition, rare variants in ESR1 and ESR2 have been implicated in various disease phenotypes. Clinical studies on these rare endocrine disorders provided clues to understand the biological functions of estrogens in the human body. This review introduces the genetic basis, phenotypes, and current management procedures of congenital disorders in estrogen biosynthesis and action.

Anthropometric biomarkers for abnormal prenatal reproductive hormone exposure in women with Mayer-Rokitanksy-Küster-Hauser syndrome, polycystic ovary syndrome, and endometriosis.

OBJECTIVE: To study whether markers of prenatal exposure to reproductive hormones are related to Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, polycystic ovary syndrome (PCOS), and endometriosis. DESIGN: Case-control study. Comparison of sex hormone-related external genital and digital characteristics in cases and controls. SETTING: University hospital. PATIENT(S): We enrolled 172 women in four groups-women with MKRH, women with PCOS, women with endometriosis, and controls (43 in each group). INTERVENTION(S): Measurement of two anthropometric biomarkers: anogenital distance and digit ratio. MAIN OUTCOME MEASURE(S): Anogenital distance was measured from the anus to the anterior clitoral surface (AGDac) and from the anus to the posterior fourchette (AGDaf). For the digit ratio we used a direct, as well as a computer-assisted graphic measurement to measure the length of the second and fourth digit. RESULT(S): After adjustment for body mass index and age, AGDac was the shortest in endometriosis and the longest in PCOS groups, with a mean difference of 10 mm (95% confidence interval 3.1-16.8). AGDaf but not AGDac measures were found to be significantly larger in the MRKH group, with a mean difference compared with controls of 2.6 mm (95% confidence interval 0.1-5.2). The digit ratio was not significantly different between the groups. CONCLUSION(S): In this study we did find limited evidence for androgen exposure during the development of MRKH. This is compatible with the hypothesis that the uterovaginal agenesis may have been the result of temporary prenatal exposure to altered gonadal hormone concentrations. For endometriosis and PCOS we confirm previously observed associations for anogenital distance reflecting possible estrogen-based and androgen-based intrauterine origins, respectively. DUTCH TRIAL REGISTRATION NUMBER: NTR7492.

46,XX DSD due to Androgen Excess in Monogenic Disorders of Steroidogenesis: Genetic, Biochemical, and Clinical Features.

The term 'differences of sex development' (DSD) refers to a group of congenital conditions that are associated with atypical development of chromosomal, gonadal, or anatomical sex. Disorders of steroidogenesis comprise autosomal recessive conditions that affect adrenal and gonadal enzymes and are responsible for some conditions of 46,XX DSD where hyperandrogenism interferes with chromosomal and gonadal sex development. Congenital adrenal hyperplasias (CAHs) are disorders of steroidogenesis that mainly involve the adrenals (21-hydroxylase and 11-hydroxylase deficiencies) and sometimes the gonads (3-beta-hydroxysteroidodehydrogenase and P450-oxidoreductase); in contrast, aromatase deficiency mainly involves the steroidogenetic activity of the gonads. This review describes the main genetic, biochemical, and clinical features that apply to the abovementioned conditions. The activities of the steroidogenetic enzymes are modulated by post-translational modifications and cofactors, particularly electron-donating redox partners. The incidences of the rare forms of CAH vary with ethnicity and geography. The elucidation of the precise roles of these enzymes and cofactors has been significantly facilitated by the identification of the genetic bases of rare disorders of steroidogenesis. Understanding steroidogenesis is important to our comprehension of differences in sexual development and other processes that are related to human reproduction and fertility, particularly those that involve androgen excess as consequence of their impairment.

XX sex chromosome complement promotes atherosclerosis in mice.

Men and women differ in circulating lipids and coronary artery disease (CAD). While sex hormones such as estrogens decrease CAD risk, hormone replacement therapy increases risk. Biological sex is determined by sex hormones and chromosomes, but effects of sex chromosomes on circulating lipids and atherosclerosis are unknown. Here, we use mouse models to separate effects of sex chromosomes and hormones on atherosclerosis, circulating lipids and intestinal fat metabolism. We assess atherosclerosis in multiple models and experimental paradigms that distinguish effects of sex chromosomes, and male or female gonads. Pro-atherogenic lipids and atherosclerosis are greater in XX than XY mice, indicating a primary effect of sex chromosomes. Small intestine expression of enzymes involved in lipid absorption and chylomicron assembly are greater in XX male and female mice with higher intestinal lipids. Together, our results show that an XX sex chromosome complement promotes the bioavailability of dietary fat to accelerate atherosclerosis.

Decidualization is Impaired in Endometrial Stromal Cells from Uterine Rudiments in Mayer-Rokitansky-Küster-Hauser Syndrome.

BACKGROUND/AIMS: Uterine rudiments from patients with Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) contain all tissues typically found in the uterus. Endometrium from the rudiments predominantly exhibits basalis-like features, and endometrial proliferative capacity in patients' epithelium and stroma is significantly lower. METHODS: This single-center, prospective study conducted at a major German university hospital compared in-vitro decidualization in cultured ESCs from MRKHS patients and hysterectomy controls. Primary ESC cultures were established from both sources. Hormone-induced prolactin and IGFBP-1 secretion served as a measure of their ability to undergo decidualization in response to hormonal stimulation. Expression levels of 8 key marker genes of decidualization were also determined. RESULTS: At day 9, mean secretion of prolactin and IGFBP-1 was significantly reduced by 89.0% and 99.5%, respectively, in MRKHS ESCs vs. hysterectomy controls, both indicating impaired decidualization of MRKHS ESCs. Key decidual markers confirmed impaired decidualization in MRKHS patients. CONCLUSION: Our results indicate that the ESCs from MRKHS patients lack hormone responsiveness as a potential sign of dysfunctional hormone receptor function, which may also play a role in the onset of MRKHS. Further studies are needed to corroborate our findings, directly address receptor function, and elucidate the role of other potential determinants of uterine development and adult function.

Identification and functional analysis of a novel LHX1 mutation associated with congenital absence of the uterus and vagina.

Congenital absence of the uterus and vagina (CAUV) is the most extreme female Müllerian duct abnormality. Several researches proposed that genetic factors contributed to this disorder, whereas the precise genetic mechanism is far from full elucidation. Here, utilizing whole-exome sequencing (WES), we identified one novel missense mutation in LHX1 (NM_005568: c.G1108A, p.A370T) in one of ten unrelated patients diagnosed with CAUV. This mutation was absent from public databases and our internal database. Through the luciferase reporter analysis, we found that the mutation could change the transcriptional activity of LHX1 and its effect on the regulation of the downstream target gene GSC, which might be associated with urogenital system development. In short, we concluded that the LHX1 may be a pathogenic gene of CAUV. Our results demonstrate the power of whole exome sequencing and gene prioritization approach as diagnostic tools in clinical practice that help make genetic diagnosis of CAUV.

Efficacy of Fibroblast Growth Factor on Epithelialization of the Neovagina in Patients with Mayer-Rokitansky-Küster-Hauser Syndrome Who Underwent Vaginoplasty.

STUDY OBJECTIVE: To evaluate the effect of fibroblast growth factor (FGF) on epithelialization of neovagina in patients with Mayer-Rokitansky-Küster-Hauser syndrome who underwent vaginoplasty. DESIGN: Observational study. SETTING: University hospital. PARTICIPANTS: Seven patients with Mayer-Rokitansky-Küster-Hauser syndrome. INTERVENTIONS: Cytological examination was done on vaginal smear samples from the site of completed epithelialization, and tissue was collected from the epithelialized part for histological evaluation. Immunostaining for estrogen receptor α, and keratin 13 and 14, and reverse transcription polymerase chain reaction (RT-PCR) analysis of the FGF receptor (FGFR) 1-4 were performed in samples from case 2 three times (ie, during the surgery, during the period of vaginal creation, and at 3 months and 6 months after the surgery). MAIN OUTCOME MEASURES: The primary outcome was the FGF effects on the epithelialization speed and FGFR expression in the neovagina. The second was the role of FGF in the mechanism of vaginal epithelial cell proliferation. RESULTS: The histological structure of the neovagina was consistent with that of normal vagina. RT-PCR analysis revealed that FGFR was expressed in the control vaginas and neovaginas. Among the FGFR subtypes, FGFR-4 was overexpressed during the process of epithelialization and its level decreased after completion of creation of the new vagina. CONCLUSION: The epithelium of the neovagina was morphologically similar to that of normal vagina. It is suggested that FGF plays the role as a growth factor.

Disorders of Sex Development with Testicular Differentiation in SRY-Negative 46,XX Individuals: Clinical and Genetic Aspects.

Virilisation of the XX foetus is the result of androgen excess, resulting most frequently from congenital adrenal hyperplasia in individuals with typical ovarian differentiation. In rare cases, 46,XX gonads may differentiate into testes, a condition known as 46,XX testicular disorders of sex development (DSD), or give rise to the coexistence of ovarian and testicular tissue, a condition known as 46,XX ovotesticular DSD. Testicular tissue differentiation may be due to the translocation of SRY to the X chromosome or an autosome. In the absence of SRY, overexpression of other pro-testis genes, e.g. SOX family genes, or failure of pro-ovarian/anti-testis genes, such as WNT4 and RSPO1, may underlie the development of testicular tissue. Recent experimental and clinical evidence giving insight into SRY-negative 46,XX testicular or ovotesticular DSD is discussed.

Oestrogen receptor alpha expression in neovaginal tissue of women following modified Abbé-McIndoe technique and in premenopausal women.

The aim of the study was to compare the expression of oestrogen receptor alpha (ERα) in neovaginal tissue of patients with vaginal agenesis following neovaginoplasty using regenerated, oxidised cellulose in premenopausal women. A prospective, observational case-control study was performed on eight patients with vaginal agenesis following modified Abbé-McIndoe neovaginoplasty and 10 control premenopausal women following benign gynaecologic surgery. 6F11 monoclonal antibody was used to determine ERα expression in the vaginal mucosa. Quantitative and qualitative evaluations were performed, respectively, in vaginal epithelium and stroma. The thickness of the vaginal epithelium was determined as the vertical distance between the basal layer cells and the apical surface of the superficial layer. The percentage of ERα-expressing cells was higher in the control group, except in the superficial zone of the epithelium. In the stromal tissue, ERα was detected in only one patient from the neovagina group compared with nine women in the control group. The neovagina group had a statistically thinner epithelium. Our study suggests that women with vaginal agenesis following modified Abbé-McIndoe neovaginoplasty using regenerated oxidised, cellulose experience relatively local hypo-oestrogenism in the first year after surgery, with repercussion in vaginal trophism.

Ovarian and uterine development and hormonal feedback mechanism in a 46 XX patient with CYP19A1 deficiency under low dose estrogen replacement.

BACKGROUND: Aromatase deficiency may result in a complete block of estrogen synthesis because of the failure to convert androgens to estrogens. In females, this results in virilisation at birth, ovarian cysts in prepuberty and lack of pubertal development but virilisation, thereafter. OBJECTIVE AND METHODS: We studied the impact of oral 17ß-estradiol treatment on ovarian and uterine development, and on LH/FSH and inhibin B during the long-term follow-up of a girl harboring compound heterozygote point mutations in the CYP19A1 gene. RESULTS: In early childhood, low doses of oral 17ß-estradiol were needed. During prepuberty treatment with slowly increasing doses of E2 resulted in normal uterine and almost normal development of ovarian volume, as well as number and size of follicles. Regarding hormonal feedback mechanisms, inhibin B levels were in the upper normal range during childhood and puberty. Low doses of estradiol did not suffice to achieve physiological gonadotropin levels in late prepuberty and puberty. However, when estradiol doses were further increased in late puberty levels of both FSH and LH declined with estradiol levels within normal range. CONCLUSION: Complete aromatase deficiency provides an excellent model of how ovarian and uterine development in relation to E2, LH, FSH and inhibin B feedback progresses from infancy to adolescence.

Aromatase deficiency in a Chinese adult man caused by novel compound heterozygous CYP19A1 mutations: effects of estrogen replacement therapy on the bone, lipid, liver and glucose metabolism.

OBJECTIVES: Aromatase deficiency is a rare disorder resulting in estrogen insufficiency in humans. It has been reported in remarkably few men with loss-of-function mutations in the CYP19A1 gene encoding the aromatase, a cytochrome P450 enzyme that plays a crucial role in the biosynthesis of estrogens from androgens. We investigated a non-consanguineous family including an adult man with clinical features of aromatase deficiency, and studied the effects of estrogen replacement in the man. METHODS: We investigated the clinical and biochemical phenotype, performed CYP19A1 mutational analysis in the family and 50 unrelated persons, studied the effects of CYP19A1 mutations on aromatase protein structure, functionally characterized the mutations by cell-based aromatase activity assays, and studied the effects of estrogen replacement on the bone, lipid, liver and glucose metabolism. RESULTS: The man with clinical features of aromatase deficiency had novel compound heterozygous CYP19A1 mutations (Y81C and L451P) that were not found in 50 unrelated persons. Three-dimensional modeling predicted that Y81C and L451P mutants disrupted protein structure. Functional studies on the basis of in vitro expression showed that Y81C and L45P mutants significantly decreased the aromatase activity and catalytic efficiency. Estrogen replacement in the man increased bone mineral density, accelerated bone maturation, improved lipid profile and liver steatosis, and improved glucose levels but not insulin resistance. CONCLUSIONS: We have identified two novel CYP19A1 missense mutations in an aromatase-deficient man. Estrogen replacement in the man shows great impact on recovering the impairments in the bone, lipid, liver and glucose metabolism, but fails to improve insulin resistance.

Bone mineral density in young women with primary ovarian insufficiency: results of a three-year randomized controlled trial of physiological transdermal estradiol and testosterone replacement.

CONTEXT: Women with primary ovarian insufficiency have significantly lower serum estradiol and T levels compared with regularly menstruating women. They also have significantly reduced bone mineral density (BMD). OBJECTIVE: The objective of the study was to evaluate the efficacy of hormone replacement in maintaining BMD in these young women. DESIGN AND SETTING: This was a randomized, double-blind, single-center, placebo-controlled clinical trial at the National Institutes of Health clinical center (Bethesda, Maryland). PARTICIPANTS: Young women with primary ovarian insufficiency participated in the study. INTERVENTIONS: We compared the effect of estradiol and progestin replacement (n = 72) vs estradiol, progestin, and T replacement (n = 73) on BMD. We also compared findings with a contemporaneous control group of normal women (n = 70). All patients received transdermal estradiol (100 µg/d) plus oral medroxyprogesterone acetate 10 mg/d (12 d/mo) for a 3-month run-in period before being randomized in a double-blinded fashion to the addition of transdermal T (150 µg/d) or placebo. MAIN OUTCOME MEASURE: Change in BMD at the femoral neck was measured by dual-energy x-ray absorptiometry. RESULTS: At screening, patients had significantly lower femoral neck BMD compared with control women (0.77 vs 0.81 g/cm(2), P = .001) and did not differ in body mass index, age at menarche, or education level. Normal control women lost femoral neck BMD over the study period, whereas patients on estradiol and progestin therapy gained BMD; and at the end of the study period, femoral neck BMD of patients on estradiol and progestin therapy did not differ from that of control women (0.80 g/cm(2) in both groups, P = .9). The addition of T showed no further benefit (percentage change in BMD 3.9 vs 2.4, respectively, P = .9). Nonetheless, using a repeated-measures model, the T group achieved a mean BMD in the femoral neck 0.015 g/cm(2) higher than the placebo group at 3 years (95% confidence interval -0.005 to 0.034, P = .13). Similar findings were observed in the lumbar spine BMD as well. CONCLUSION: Long-term physiological transdermal estradiol replacement in combination with oral medroxyprogesterone acetate restores mean femoral neck BMD to normal in young women with spontaneous 46,XX primary ovarian insufficiency. However, the addition of physiological transdermal T replacement did not provide additional benefit.

Gene expression profile of patients with Mayer-Rokitansky-Küster-Hauser syndrome: new insights into the potential role of developmental pathways.

Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) is a rare disease characterized by congenital aplasia of uterus and vagina. Although many studies have investigated several candidate genes, up to now none of them seem to be responsible for the aetiology of the syndrome. In our study, we identified differences in gene expression profile of in vitro cultured vaginal tissue of MRHKS patients using whole-genome microarray analysis. A group of eight out of sixteen MRKHS patients that underwent reconstruction of neovagina with an autologous in vitro cultured vaginal tissue were subjected to microarray analysis and compared with five healthy controls. Results obtained by array were confirmed by qRT-PCR and further extended to other eight MRKHS patients. Gene profiling of MRKHS patients delineated 275 differentially expressed genes, of which 133 downregulated and 142 upregulated. We selected six deregulated genes (MUC1, HOXC8, HOXB2, HOXB5, JAG1 and DLL1) on the basis of their fold change, their differential expression in most patients and their relevant role in embryological development. All patients showed upregulation of MUC1, while HOXB2 and HOXB5 were downregulated, as well as Notch ligands JAG1 and DLL1 in the majority of them. Interestingly, HOXC8 was significantly upregulated in 47% of patients, with a differential expression only in MRKHS type I patients. Taken together, our results highlighted the dysregulation of developmental genes, thus suggesting a potential alteration of networks involved in the formation of the female reproductive tract and providing a useful clue for understanding the pathophysiology of MRKHS.

Aromatase and estrogen receptor α deficiency.

Studies on the phenotypes of women and men with mutations disrupting estrogen biosynthesis and action have significantly advanced our knowledge of the physiologic roles of estrogen in humans. Aromatase deficiency results from autosomal recessive inheritance of mutations in the CYP19A1 gene. It gives rise to ambiguous genitalia in 46,XX fetuses. At puberty, affected girls have hypergonadotropic hypogonadism, do not develop secondary sexual characteristics, and exhibit progressive virilization. The affected 46,XY men have normal male sexual differentiation and pubertal maturation. These men, however, are extremely tall and have eunucoid proportions with continued linear growth into adulthood, severely delayed epiphyseal closure, and osteoporosis due to estrogen deficiency. Although estrogen has been shown to be essential for normal sperm production and function in mice, its role in fertility is not clear in men. Thus far, one man and an unrelated woman with estrogen resistance due to mutations in the estrogen receptor α (ESR1) gene have been described. Their clinical presentations are similar to that of aromatase-deficient men and women.

Genomic basis of aromatase excess syndrome: recombination- and replication-mediated rearrangements leading to CYP19A1 overexpression.

CONTEXT: Genomic rearrangements at 15q21 have been shown to cause overexpression of CYP19A1 and resultant aromatase excess syndrome (AEXS). However, mutation spectrum, clinical consequences, and underlying mechanisms of these rearrangements remain to be elucidated. OBJECTIVE: The aim of the study was to clarify such unsolved matters. DESIGN, SETTING, AND METHODS: We characterized six new rearrangements and investigated clinical outcome and local genomic environments of these rearrangements and of three previously reported duplications/deletions. RESULTS: Novel rearrangements included simple duplication involving exons 1-10 of CYP19A1 and simple and complex rearrangements that presumably generated chimeric genes consisting of the coding region of CYP19A1 and promoter-associated exons of neighboring genes. Clinical severities were primarily determined by the copy number of CYP19A1 and the property of the fused promoters. Sequences at the fusion junctions suggested nonallelic homologous recombination, nonhomologous end-joining, and replication-based errors as the underlying mechanisms. The breakpoint-flanking regions were not enriched with GC content, palindromes, noncanonical DNA structures, or known rearrangement-associated motifs. The rearrangements resided in early-replicating segments. CONCLUSIONS: These results indicate that AEXS is caused by duplications involving CYP19A1 and simple and complex rearrangements that presumably lead to the usage of cryptic promoters of several neighboring genes. Our data support the notion that phenotypes depend on the dosage of CYP19A1 and the characteristics of the fused promoters. Furthermore, we show that the rearrangements in AEXS are generated by both recombination- and replication-mediated mechanisms, independent of the known rearrangement-inducing DNA features or late-replication timing. Thus, AEXS represents a unique model for human genomic disorders.

Long-term clinical data and molecular defects in the STAR gene in five Greek patients.

CONTEXT: Steroidogenic acute regulatory (STAR) gene mutations lead to adrenal and gonadal failure. Interesting, though as yet unexplained, features are the formation of ovarian cysts and the potential presence of CNS findings. OBJECTIVE: To report biochemical, genetic, and long-term clinical data in five Greek patients from four different families with STAR gene defects (three 46,XX and two 46,XY). METHODS AND RESULTS: All patients presented in early infancy with adrenal insufficiency. The STAR gene mutation c.834del11bp, detected in three of our patients, completely alters the carboxyl end of the STAR protein and has not thus far been described in other population groups. These three patients belong to three separate families, possibly genetically related, as they live in different villages located in a small region of a Greek island. However, their interrelationship has not been proven. A second mutation, p.W250X, detected in our fourth family, was previously described only in two Serbian patients. Ovarian cysts were detected ultrasonographically in our 46,XX patients and seemed to respond to a low dose of a contraceptive. The histology of an excised ovarian cyst was diagnosed as a corpus luteum (CL) cyst. In two out of the four patients who had undergone brain magnetic resonance imaging, asymptomatic Chiari-1 malformation was observed. CONCLUSIONS: The occurrence of STAR gene mutation c.834del11bp in three families living in a restricted geographic region could indicate either a founder effect or simply reflect a spread of this defect in a highly related population. The ovarian histological findings suggest that ovarian cysts detected ultrasonographically in 46,XX individuals with STAR gene defects may be CL cysts. The Chiari-1 malformation in two of our patients may be part of the STAR gene mutation phenotype. Nevertheless, more data are needed to confirm or disprove the existence of specific CNS pathology in patients with STAR gene mutations.

Steroidogenic factor-1 and human disease.

Steroidogenic factor-1 (SF-1) (Ad4BP, NR5A1) is a nuclear receptor that plays a key role in adrenal and reproductive development and function. Deletion of the gene encoding Sf-1 (Nr5a1) in mice results in severe developmental defects of the adrenal gland and gonad. Consequently, initial work on the potential effects of SF-1 disruption in humans focused on individuals with primary adrenal failure, a 46,XY karyotype, complete gonadal dysgenesis, and Müllerian structures. This is a rare phenotype, but has been reported on two occasions, because of alterations that affect key DNA-binding domains of SF-1. Attention then turned to a potential wider role of SF-1 in human adrenal and reproductive disorders. Although changes in SF-1 only very rarely cause isolated adrenal failure, it is emerging that variations in SF-1 are a surprisingly frequent cause of reproductive dysfunction in humans. In 46,XY disorders of sex development, a spectrum of phenotypes has been reported including severe and partial forms of gonadal (testicular) dysgenesis, hypospadias, anorchia with microphallus, and even male factor infertility. In 46,XX females, alterations in SF-1 are associated with primary ovarian insufficiency. Thus, SF-1 seems be a more significant factor in human reproductive health than was first envisioned, with implications for adults as well as children.

Impact of estrogen replacement throughout childhood on growth, pituitary-gonadal axis and bone in a 46,XX patient with CYP19A1 deficiency.

BACKGROUND: The adequate replacement dose of estrogens during infancy and childhood is still not known in girls. Aromatase deficiency offers an excellent model to study how much estrogens are needed during infancy, childhood and adulthood. OBJECTIVES: We studied the impact of oral 17ß-estradiol treatment, on longitudinal growth, bone age maturation, pituitary gonadotropin feedback, multicystic ovaries and bone mass in the long-term follow-up of a girl compound heterozygote for two point mutations of the CYP19A1 gene. RESULTS: Low doses of 17ß-estradiol were needed to achieve normal height velocity and adequate bone age maturation from early childhood on. Serum estradiol levels needed for breast development and for the appearance of an endometrial reflex were not sufficient to achieve physiological gonadotropin levels. Without 17ß-estradiol treatment the ovaries of the patient showed a multicystic appearance, which reversed on 17ß-estradiol replacement. Bone mass was within normal ranges during the whole follow-up period. CONCLUSION: In summary, we have shown that estradiol is needed not only in puberty but also in childhood for normal growth, bone maturation and achievement of normal bone mass. Particularly, this observation underscores the importance of early low-dose estrogen replacement also in other estrogen-deficient conditions as for instance in Turner's syndrome.

Role of a disordered steroid metabolome in the elucidation of sterol and steroid biosynthesis.

In 1937 Butler and Marrian found large amounts of the steroid pregnanetriol in urine from a patient with the adrenogenital syndrome, a virilizing condition known to be caused by compromised adrenal secretion even in this pre-cortisol era. This introduced the concept of the study of altered excretion of metabolites as an in vivo tool for understanding sterol and steroid biosynthesis. This approach is still viable and has experienced renewed significance as the field of metabolomics. From the first cyclized sterol lanosterol to the most downstream product estradiol, there are probably greater than 30 steps. Based on a distinctive metabolome clinical disorders have now been attributed to about seven post-squalene cholesterol (C) biosynthetic steps and around 15 en-route to steroid hormones or needed for further metabolism of such hormones. Forty years ago it was widely perceived that the principal steroid biosynthetic defects were known but interest rekindled as novel metabolomes were documented. In his career this investigator has been involved in the study of many steroid disorders, the two most recent being P450 oxidoreductase deficiency and apparent cortisone reductase deficiency. These are of interest as they are due not to mutations in the primary catalytic enzymes of steroidogenesis but in ancillary enzymes needed for co-factor oxido-reduction A third focus of this researcher is Smith-Lemli-Opitz syndrome (SLOS), a cholesterol synthesis disorder caused by 7-dehydrocholesterol reductase mutations. The late George Schroepfer, in whose honor this article has been written, contributed greatly to defining the sterol metabolome of this condition. Defining the cause of clinically severe disorders can lead to improved treatment options. We are now involved in murine gene therapy studies for SLOS which, if successful could in the future offer an alternative therapy for this severe condition.