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At least 19 recordsLinked to original sources
PubMed2003

Apparent pregnene hydroxylation deficiency (APHD): seeking the parentage of an orphan metabolome.

This paper collates and reviews a number of clinical cases published over the last 20 years that we believe describe a novel steroid disorder associated with genital ambiguity. The authors of the original papers were unable to diagnose their patients conclusively. Females with the disorder are frequently masculinized and males feminized. The central feature of steroid biosynthesis is overproduction of pregnenolone and progesterone, which results in elevated concentrations of these steroids in plasma and exaggerated response to ACTH. Equivalent urinary data show elevated excretion of 5-pregnene-3beta,20alpha-diol (the major pregnenolone metabolite) and pregnanediol. Another notable feature of the metabolome is the relatively high plasma concentrations of the analytes for 21-hydroxylase deficiency (17-hydroxyprogesterone) and 17-hydroxylase deficiency (corticosterone). Correspondingly, metabolites of these steroids are prominent in urine. Circulating cortisol was generally normal but had blunted response to ACTH. Taken together these features pointed to an apparent relative deficiency of 21- and 17-hydroxylation, but no mutations have been found in the enzymes responsible for these transformations in cases where it has been investigated. The simultaneous presence of mutated genes on two chromosomes is also extremely unlikely. Until more is known of this interesting condition, and the genetic cause (presumed) is known, we propose naming it apparent pregnene hydroxylation deficiency (APHD). The metabolome is similar to that of isolated 17,20-lyase deficiency with which it has been confused. In fact, diminished (but not isolated) lyase activity is probably a significant factor in some patients. We believe that the attenuated steroid hydroxylation could be associated with deficiency of the required co-factors and modulators of hydroxylation such as P450 reductase and cytochrome b5. Post-translational modifications of the hydroxylases such as phosphorylation/dephosphorylation have also been suggested as influential in directionally regulating steroid synthesis. Some patients with the disorder have no dysmorphology apart from genital malformations while others have skeletal abnormalities attributed to Antley-Bixler syndrome. Whether we are looking at different conditions, or a severity continuum is not known. It is possible that the presence of this metabolome may become a required feature for diagnosis of Antley-Bixler syndrome. A combination of intersex phenotype and dysmorphology suggests that an error in a transcription factor may be an alternative to hydroxylation redox partner deficit as causative of the condition.The virilization of female patients with APHD probably results from a transient hyperandrogenism prior to birth.

Adolescent↗
PubMed2004

A male twin infant with skull deformity and elevated neonatal 17-hydroxyprogesterone: a prismatic case of P450 oxidoreductase deficiency.

We report on a male twin infant who presented with brachy-turri-cephaly, frontal bossing, large anterior fontanelle, low set and malformed ears, and mild arachnodactyly. He had normal male genitalia. There was no evidence for maternal virilization during pregnancy. The pattern of malformations resembled Antley-Bixler-Syndrome (ABS). However, sequencing analysis of the fibroblast growth factor receptor 2 gene (FGFR2) did not reveal mutations. The boy's twin sister did not show any somatic or endocrine abnormalities. In the boy, neonatal screening for congenital adrenal hyperplasia was positive with moderately elevated 17-hydroxyprogesterone. Sequence analysis of his CYP21 gene did not reveal any mutations. The short synacthen test revealed an exaggerated 17-hydroxyprogesterone and a blunted cortisol response. Urinary steroid profiling by gas chromatography-mass spectrometry (GC-MS) revealed a unique steroid metabolome suggestive of impaired activity of both 17-hydroxylase and 21-hydroxylase. Clinical and metabolic findings therefore were compatible with the recently described variant of congenital adrenal hyperplasia, P450 oxidoreductase deficiency (ORD). Subsequently, sequencing analysis of CPR, the gene encoding P450 oxidoreductase (OR), revealed a homozygous mutation in the patient, resulting in an amino acid exchange in position 284 of the OR protein (A284P). Both the female twin sister and the parents were heterozygous for the A284P mutation. P450 oxidoreductase deficiency represents a novel autosomal recessively inherited form of congenital adrenal hyperplasia. Its characteristic steroid metabolome can readily be detected by GC-MS analysis of spot urine. Clinical features may include an ABS phenotype, ambiguous genitalia (virilization in girls, feminization in boys), and glucocorticoid deficiency. If required, hydrocortisone replacement should be provided.

17-alpha-Hydroxyprogesterone↗
PubMed1996

Evidence for independent modulation of human 11-HSD and 5 alpha/5 beta reductase activities.

The increased ratio of 5 alpha to 5 beta reduced steroids associated with apparent mineralocorticoid excess (AME) may be a necessary consequence of altered 11 beta-hydroxysteroid dehydrogenase (11-HSD) activity. In order to test this hypothesis we have compared changes in 11-HSD activity and 5 alpha/5 beta reduction in a variety of clinical and experimental conditions. The ratio of 11-oxo/11 beta-hydroxy metabolites of cortisol (11-oxo/11-OH FM) was used as an index of 11-HSD activity and the ratio of allotetrahydrocortisol/ tetrahydrocortisol (allo THF/THF) was used as an index of 5 alpha/5 beta reduction. Ratios were derived from 24 hour urinary steroid profiles measured by high resolution gas chromatography. The clinical conditions studied were Cushing's Syndrome, Major Depression and hirsutism. In each study, the patient group were compared with age-matched healthy controls. For the experimental conditions, subjects treated with either hydrocortisone, dexamethasone, metyrapone or finasteride acted as their own controls. No consistent relationship was found between changes in the ratios of 11-oxo/11-OH FM and allo THF/THF. We conclude that there is no evidence of consistent metabolic interaction between 11-HSD and 5 alpha/5 beta reductase activities under a wide range of conditions. Furthermore, the patterns of metabolic changes seen in these conditions are no less characteristic, although more subtle, than the well-documented metabolic changes seen in inborn errors of steroid metabolism.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed2006

Micellar solubilisation of cholesterol is essential for absorption in humans.

BACKGROUND AND AIMS: Intralumenal bile acid (BA) concentrations have a profound effect on cholesterol absorption. We performed studies to assess the effects of markedly reduced lumenal BA on cholesterol absorption in children with inborn errors in BA synthesis and the role of micellar solubilisation of cholesterol on its absorption in an animal model using human intestinal contents. METHODS: We studied five subjects: two with 3beta hydroxy-C27 steroid dehydrogenase isomerase deficiency (3-HSD), two with Delta(4)-3-oxosteroid 5beta reductase deficiency (5beta reductase), and one with 2-methylacyl CoA racemase deficiency (racemase). Subjects were studied on supplemental BA therapy and three weeks after withdrawal of supplements. During each treatment period a liquid meal was consumed. Duodenal samples were collected and analysed, and cholesterol absorption and cholesterol fractional synthetic rates were measured. Human intralumenal contents were infused in a bile diverted rat lymph fistula model to assess micellar versus vesicular absorption of cholesterol. RESULTS: Without BA supplementation, intralumenal BA concentrations were below the critical micellar concentration (CMC) whereas intralumenal BAs increased to above the CMC in all subjects on BA supplementation. Lumenal cholesterol was carried primarily as vesicles in untreated subjects whereas it was carried as both micelles and vesicles in treated subjects. Cholesterol absorption increased approximately 55% in treated compared with untreated subjects (p=0.041), with a simultaneous 70% decrease in synthesis rates (p=0.029). In the rat lymph fistula model, minimal vesicular cholesterol was absorbed whereas vesicular and micellar fatty acid and phospholipid were comparably absorbed. CONCLUSIONS: Increasing micellar cholesterol solubilisation by supplemental BA in subjects with inborn errors of BA synthesis leads to an improvement in cholesterol absorption and reduction in cholesterol synthesis due to improved micellar solubilisation of cholesterol.

3-Hydroxysteroid Dehydrogenases↗
PubMed1983

Distinctive plasma aldosterone, 18-hydroxycorticosterone, and 18-hydroxydeoxycorticosterone profile in the 21-, 17 alpha-, and 11 beta-hydroxylase deficiency types of congenital adrenal hyperplasia.

Forms of congenital adrenal hyperplasia resulting from deficient steroid hydroxylation at positions 21, 17 alpha, and 11 beta have several similar clinical and biochemical characteristics. Biochemical diagnosis has been dependent on the demonstration of elevated plasma or urinary concentrations of metabolites of the immediate biosynthetic precursor before the enzymatic block, especially after stimulation with adrenocorticotropin. Aldosterone, 18-hydroxycorticosterone, and 18-hydroxydeoxycorticosterone are not closely involved nor are they immediate precursors of any of these enzymatic defects. However, simultaneous determination of the baseline plasma levels of these steroids in patients with nonsodium-losing 21-hydroxylase deficiency (n = 12), 17 alpha-hydroxylase deficiency (n = 6), and 11 beta-hydroxylase deficiency (n = 2) revealed a consistent and distinct pattern (mean +/- SEM in nanograms per deciliter): aldosterone (28.1 +/- 2.8) and 18-hydroxycorticosterone (84.5 +/- 9.2) levels were elevated and 18-hydroxydeoxycorticosterone (8.0 +/- 0.8) levels were within normal limits in 21-hydroxylase deficiency; 18-hydroxycorticosterone (327.2 +/- 73.9) and 18-hydroxydeoxycorticosterone (236.0 +/- 33.8) levels were elevated and aldosterone (3.5 +/- 0.6) levels were reduced in 17 alpha-hydroxylase deficiency; levels of all three steroids (aldosterone 2.6 +/- 0.4, 18-hydroxycorticosterone 5.1 +/- 3.1, 18-hydroxydeoxycorticosterone 0.9 +/- 0.1) were reduced in 11 beta-hydroxylase deficiency. It is suggested that simultaneous measurement of these three steroids can be useful in identifying and further characterizing each of these forms of congenital adrenal hyperplasia.

18-Hydroxycorticosterone↗
PubMed1997

Definitive diagnosis of enzymatic deficiencies of steroidogenesis in at-risk newborns and infants by urinary marker analysis using GC/MS-SIM.

A simplified urinary marker analysis for diagnosis of congenital adrenal hyperplasia (CAH) and 5alpha-reductase deficiency in infancy by GC/MS-SIM is introduced. The analysis was performed in 161 patients aged 3-90 days, 99 females and 62 males. CAH due to 21-hydroxylase deficiency was diagnosed in 61 patients (42 females and 19 males; in 10 cases simple virilizing form and in 51 patients salt-wasting form) and CAH induced by 3beta-hydroxysteroid dehydrogenase deficiency without salt loss in 1 female patient. In 2 full-term newborns and 6 preterm infants, a false-positive diagnosis of CAH, which had been based on serum steroid evaluation, was made. In these cases, increased excretion of fetal adrenal zone steroids was confirmed as a possible source of false-positive serum 11-deoxycortisol and 17alpha-hydroxyprogesterone values. Lack of fetal adrenal zone steroid metabolites in 2 male newborns with salt loss symptoms led to the diagnosis of adrenal insufficiency due to X-linked adrenal hypoplasia and adrenal hemorrhage. A single analysis of urinary CAH markers by the very sensitive and selective GC/MS-SIM method can replace numerous assays of various steroids that must be carried out for positive diagnosis of abnormal steroidogenesis in infancy.

Adrenal Cortex Hormones↗
PubMed2003

Inborn errors of adrenal steroidogenesis.

Congenital adrenal hyperplasia (CAH) refers to a family of inherited disorders of adrenal steroidogenesis in which each disorder is characterized by a specific enzyme deficiency that impairs cortisol production by the adrenal cortex. The enzymes most commonly affected are 21-hydroxylase (21-OH), 11beta-hydroxylase, 3beta-hydroxysteroid dehydrogenase, and less often, 17alpha-hydroxylase/17,20-lyase and cholesterol desmolase. Many of the corresponding genes for the described enzymes have been isolated and characterized, and specific mutations causing CAH have been identified. In classical CAH (simple virilizing and salt wasting forms), androgen excess causes external genital ambiguity in newborn females and progressive postnatal virilization in both sexes. In nonclassical CAH, 21-OHD is partial and occurs with milder symptoms. A deficiency of 11beta-Hydroxylase deficiency results in ambiguous genitalia in the newborn genetic female and androgen excess and hypertension in both males and females. In 3beta-hydroxysteroid deficiency adrenal and gonadal androgen production is deficient resulting in incomplete genital development in genetic males and limited androgen affect in females. Two less frequent causes of CAH 17alpha-Hydroxylase/17,20-lyase and cholesterol desmolase result in external female genitalia in both sexes. Hormonal diagnosis is described for each disorder.

3-Hydroxysteroid Dehydrogenases↗
PubMed2001

Congenital adrenal hyperplasia: transition from chil dhood to adulthood.

Congenital adrenal hyperplasia (CAH) is a group of disorders caused by inborn errors of steroid metabolism. The most common form owing to 21-hydroxylase deficiency (CAH-21OHD) is present in about 1:10,000- 1:15,000 live births worldwide. In its classic salt-wasting form (-66-75% of cases) patients may suffer potentially lethal adrenal insufficiency. Non-salt-wasting forms of CAH-21 OHD are recognized by genital ambiguity in affected females, and by signs of androgen excess in later childhood in males. Non-classic CAH-21 OHD may be detected in up to 1-3% of certain populations, and is often mistaken for idiopathic precocious pubarche in children or polycystic ovary syndrome in young women. This chapter will address issues relating to transition of CAH care from the pediatric to the adult endocrinologist.

Adolescent↗
PubMed1989

Polymorphism of cytochrome P-450 in humans.

A number of different cytochrome P-450 proteins are found in human liver and other tissues. These enzymes oxidize drugs and carcinogens as well as endogenous chemicals such as steroids and eicosanoids. As Peter Guengerich explains, activities of individual cytochrome P-450 enzymes vary among individuals as a result of both genetic and environmental influences; in some cases, the mechanisms are known. Such variation can have major influences in determining drug toxicity, inborn errors of steroid metabolism, and possibly cancer risk.

Cytochrome P-450 Enzyme System↗
PubMed2006

The genetics of ACTH resistance syndromes.

Inherited adrenocorticotropin (ACTH) resistance diseases are rare and include triple A syndrome and familial glucocorticoid deficiency (FGD). These conditions show genetic heterogeneity, i.e., the identical clinical phenotype may result from defects in more than one gene. Clinically, FGD is characterized only by ACTH resistance, while the triple A syndrome exhibits a variety of additional clinical features. FGD is caused by mutations in the ACTH receptor (melanocortin 2 receptor, MC2R) and the recently identified melanocortin 2 receptor accessory protein (MRAP) genes. In addition, linkage to a locus on chromosome 8 has been demonstrated. The identification of further genes in ACTH resistance syndromes may reveal novel aspects of MC2R signalling and trafficking. This review will summarize the clinical, biochemical and genetic aspects of these rare but informative diseases.

Adrenal Insufficiency↗
PubMed1999

Regulation of bile acid biosynthesis.

This article provides a review of the pathways through which cholesterol is degraded to bile acids. Regulation of key enzymes in the bile acid biosynthestic pathways is discussed. The important role of these pathways in the maintenance of cholesterol homeostasis and the possible therapeutic implications for the treatment of hypercholesterolemia are emphasized.

Animals↗
PubMed2004

Genetic and molecular aspects of hypospadias.

Hypospadias, a midline fusion defect of the male ventral urethra, is a relatively common genital anomaly occurring in 0.3 - 7 of 1000 live male births. The anatomical location of the misplaced urethral meatus determines the severity of this anomaly with the severity increasing from distal to proximal. Glandular and penile hypospadias, the most common forms, often appear as an isolated anomaly and account for the majority of hypospadias, whereas about 20 % are classified as scrotal and perineal types. These latter forms frequently occur in association with other genital anomalies such as microphallus, bifid scrotum, penoscrotal transposition, and cryptorchidism, and may represent an intersex phenotype. Besides a higher incidence in consanguineous families and a suggested recessive inheritance, in other families a dominant transmission is likely. The recurrence risk in the next generation seems to be correlated with the severity of hypospadias. Only 30 % of severe hypospadias can be attributed to defects in the synthesis of testosterone or adrenal steroid hormones, receptor defects, syndrome-associated hypospadias, chromosomal anomalies, defects in other genetic factors, or exogenous forms. To identify the underlying causes of the remaining 70 % "idiopathic" hypospadias, familial and twin studies were performed. Familial studies can help identify gene loci and, subsequently, candidate genes by mutational analysis. Either linkage analysis in large families with many affected individuals suspicious for a monogenic trait or association studies in cases of a complex inheritance in many families with a few affected individuals can be performed. Microarrays and proteomics can help detect gene expression or protein differences. Furthermore, genetically modified animal models can be used to detect phylogenetically homologous genes in man. In addition to an optimal documentation and acquisition of blood and tissue samples this requires a close cooperation between clinicians in the operative and non-operative specialties as well as geneticists.

Abnormalities, Multiple↗
PubMed2004

Folliculogenesis is impaired and granulosa cell apoptosis is increased in leptin-deficient mice.

Leptin purportedly plays an important role in pubertal development in a number of mammalian species. Adult leptin-deficient (ob/ob) female mice are infertile, but the mechanisms responsible for the reproductive failure have not been fully elucidated. The major objective of the current study was to assess the effects of a leptin deficiency on ovarian folliculogenesis and apoptosis. Beginning at 4 wk of age, control (n = 8) and ob/ob (n = 7) mice were weighed and examined daily for vaginal opening. After 3 wk the mice were killed, and the reproductive organs were weighed. Ovaries were paraffin-embedded for hematoxylin and eosin histology, TUNEL assay, and immunohistochemistry for Fas, Fas ligand (FasL), and proliferating cell nuclear antigen (PCNA). Vaginal opening was delayed, uteri were smaller, and the number of primordial follicles and total number of ovarian follicles were subnormal in ob/ob animals. Leptin-deficient animals also had a higher number of atretic follicles than controls. Granulosa cells (predominantly in preantral and early antral follicles) of ob/ob mice exhibited increased apoptotic activity as documented by TUNEL assay and elevated expression of the apoptotic markers Fas and FasL, compared with that in control animals. Ovarian expression of PCNA, a marker of DNA replication, repair, or both, did not differ between ob/ob and control mice. The data suggest that a leptin deficiency in mice is associated with impaired folliculogenesis, which results in increased follicular atresia. This impairment may be one of the causative components of infertility in leptin-deficient animals.

Aging↗