Five novel mutations in CYP11B2 gene detected in patients with aldosterone synthase deficiency type I: Functional characterization and structural analyses.

CONTEXT: Aldosterone synthase deficiency (ASD) is an important differential diagnosis of diseases associated with salt wasting in early infancy. OBJECTIVE: The objective of this study was to investigate the molecular basis for the disorder by (1) molecular genetic analysis in the CYP11B2 from patients suffering from ASD type I. (2) Functional characterization of the missense mutant gene products. (3) Structural simulation of the missense mutations. RESULTS: Patient 1 was a homozygous carrier of a novel mutation located in exon 4 causing a premature stop codon (p.W260X). Patient 2 was analyzed to be compound heterozygous for two novel mutations: The first was an insertion mutation (p.G206WfsX51), and the second was a deletion mutation (p.L496SfsX169). Two siblings (patients 3 and 4) were compound heterozygous carriers of two novel missense mutations (p.S315R, p.R374W). The expression studies of the mutant proteins in COS-1 cells showed a complete absence of CYP11B2 activity of p.S315R and p.R374W mutants for the conversion of 11-deoxycorticosterone to aldosterone. A 3-D model of CYP11B2 p.S315R and p.R374W indicated a change of the hydrogen bond network which might explain the cause of the dysfunction. CONCLUSION: We have identified the first CYP11B2 gene defects in two Polish families associated with phenotypes of ASD type I. Analysis of the enzymatic function as a complementary procedure to genotyping revealed data for understanding the clinical phenotype of ASD. Molecular modeling of the mutated enzyme provided a rational basis for understanding the changed activities of the mutant proteins.

Steroid biomarkers and genetic studies reveal inactivating mutations in hexose-6-phosphate dehydrogenase in patients with cortisone reductase deficiency.

CONTEXT: Cortisone reductase deficiency (CRD) is characterized by a failure to regenerate cortisol from cortisone via 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), resulting in increased cortisol clearance, activation of the hypothalamic-pituitary-axis (HPA) and ACTH-mediated adrenal androgen excess. 11beta-HSD1 oxoreductase activity requires the reduced nicotinamide adenine dinucleotide phosphate-generating enzyme hexose-6-phosphate dehydrogenase (H6PDH) within the endoplasmic reticulum. CRD manifests with hyperandrogenism resulting in hirsutism, oligo-amenorrhea, and infertility in females and premature pseudopuberty in males. Recent association studies have failed to corroborate findings that polymorphisms in the genes encoding H6PDH (R453Q) and 11beta-HSD1 (Intron 3 inserted adenine) interact to cause CRD. OBJECTIVE: Our objective was to reevaluate the genetics and steroid biochemistry of patients with CRD. DESIGN: We analyzed 24-h urine collection for steroid biomarkers by gas chromatography/mass spectrometry and sequenced the HSD11B1 and H6PD genes in our CRD cohort. PATIENTS: Patients included four cases presenting with hyperandrogenism and biochemical features clearly indicative of CRD. RESULTS: Gas chromatography/mass spectrometry identified steroid biomarkers that correlated with CRD in each case. Three cases were identified as homozygous (R109AfsX3, Y316X, and G359D) and one case identified as compound heterozygous (c.960G-->A and D620fsX3) for mutations in H6PD. No mutations affecting enzyme activity were identified in the HSD11B1 gene. Expression and activity assays demonstrate loss of function for all reported H6PDH mutations. CONCLUSIONS: CRD is caused by inactivating mutations in the H6PD gene, rendering the 11beta-HSD1 enzyme unable to operate as an oxoreductase, preventing local glucocorticoid regeneration. These data highlight the importance of the redox control of cortisol metabolism and the 11beta-HSD1-H6PDH pathway in regulating hypothalamic-pituitary-adrenal axis activity.

[The Smith-Lemli-Opitz syndrome--case report, early diagnosis]. / Zespól Smitha, Lemlego i Opitza--opis przypadku, wczesna diagnostyka.

Smith-Lemli-Opitz syndrome (SLOS) is one of the most frequent metabolic disorders in Poland and manifests itself with multiple congenital anomalies, psychomotor delay and intellectual disability. It is caused by mutations in DHCR7 gene, which codes one of the cholesterol biosynthesis enzymes. Clinical diagnosis of the syndrome is difficult due to lack of pathognomonic features and their variable expression. Despite high carrier frequency in Poland, SLO syndrome is rarely suspected and recognized. Its early diagnosis is essential, mainly because of high genetic risk (25%) as well as possibilities of treatment. Authors present a female-newborn, diagnosed with SLOS during the neonatal period. The diagnosis was based on biochemical and molecular tests. Mutations in DHCR7 gene have been found in both, the child and the parents.

Phenotypic, metabolic, and molecular genetic characterization of six patients with congenital adrenal hyperplasia caused by novel mutations in the CYP11B1 gene.

Congenital adrenal hyperplasia (CAH) is an autosomal recessive inherited disorder of steroidogenesis. Steroid 11ß-hydroxylase deficiency (11ß-OHD) due to mutations in the CYP11B1 gene is the second most common form of CAH. In this study, 6 patients suffering from CAH were diagnosed with 11ß-OHD using urinary GC-MS steroid metabolomics analysis. The molecular basis of the disorder was investigated by molecular genetic analysis of the CYP11B1 gene, functional characterization of splicing and missense mutations, and analysis of the missense mutations in a computer model of CYP11B1. All patients presented with abnormal clinical signs of hyperandrogenism. Their urinary steroid metabolomes were characterized by excessive excretion rates of metabolites of 11-deoxycortisol as well as metabolites of 11-deoxycorticosterone, and allowed definite diagnosis. Patient 1 carries compound heterozygous mutations consisting of a novel nonsense mutation p.Q102X (c.304C>T) in exon 2 and the known missense mutation p.T318R (c.953C>G) in exon 5. Two siblings (patient 2 and 3) were compound heterozygous carriers of a known splicing mutation c.1200+1G>A in intron 7 and a known missense mutation p.R448H (c.1343G>A) in exon 8. Minigene experiments demonstrated that the c.1200+1G>A mutation caused abnormal pre-mRNA splicing (intron retention). Two further siblings (patient 4 and 5) were compound heterozygous carriers of a novel missense mutation p.R332G (c.994C>G) in exon 6 and the known missense mutation p.R448H (c.1343G>A) in exon 8. A CYP11B1 activity study in COS-1 cells showed that only 11% of the enzyme activity remained in the variant p.R332G. Patient 6 carried a so far not described homozygous deletion g.2470_5320del of 2850 bp corresponding to a loss of the CYP11B1 exons 3-8. The breakpoints of the deletion are embedded into two typical 6 base pair repeats (GCTTCT) upstream and downstream of the gene. Experiments analyzing the influence of mutations on splicing and on enzyme function were applied as complementary procedures to genotyping and provided a rational basis for understanding the clinical phenotype of CAH.

Congenital adrenal hyperplasia caused by mutant P450 oxidoreductase and human androgen synthesis: analytical study.

BACKGROUND: Congenital adrenal hyperplasia with apparent combined P450C17 and P450C21 deficiency is associated with accumulation of steroid metabolites, indicating impaired activity of 17alpha-hydroxylase and 21-hydroxylase. However, no mutations have been reported in the CYP17 and CYP21 genes, which encode these P450 enzymes. Affected girls are born with ambiguous genitalia, but their circulating androgens are low, and virilisation does not progress. We aimed to investigate the underlying molecular basis of congenital adrenal hyperplasia with apparent combined P450C17 and P450C21 deficiency in affected children. METHODS: We did sequence analysis of the human gene encoding P450 oxidoreductase, an enzyme that is important in electron transfer from NADPH to P450C17 and P450C21. We studied two unrelated families with a total of three affected children and 100 healthy controls. Wild-type and mutant P450 oxidoreductase proteins were bacterially expressed, purified, and assayed for cytochrome c reductase activity. FINDINGS: We identified four mutations encoding single aminoacid changes in P450 oxidoreductase. All patients were compound heterozygotes, whereas their parents and an unaffected sibling harboured a mutation in only one allele. By contrast, no mutations were noted in the controls. Bacterial expression of recombinant mutant proteins revealed deficient or reduced enzyme activity. INTERPRETATION: Molecular pathogenesis of this form of congenital adrenal hyperplasia is caused by mutations in the gene encoding P450 oxidoreductase. Deficiency of this enzyme could suggest an alternative pathway in human androgen synthesis, present only in fetal life, which explains the combination of antenatal androgen excess and postnatal androgen deficiency.

The diagnosis of congenital adrenal hyperplasia in the newborn by gas chromatography/mass spectrometry analysis of random urine specimens.

Definitive neonatal diagnosis of congenital adrenal hyperplasia (CAH) is frequently complicated by normal 17-hydroxyprogesterone levels in 21-hydroxylase-deficient patients, residual maternal steroids, and other interfering substances in neonatal blood. In an effort to improve the diagnosis, we developed a gas chromatography/mass spectrometry method for simultaneous measurement of 15 urinary steroid metabolites as early as the first day of life. Furthermore, we developed 11 precursor/product ratios that diagnose and clearly differentiate the four enzymatic deficiencies that cause CAH. Random urine samples from 31 neonatal 21-hydroxylase-deficient patients and 59 age-matched normal newborns were used in the development. Additionally, samples from two 11 beta-hydroxylase-deficient patients and one patient each for 17 alpha-hydroxylase and 3 beta-hydroxysteroid dehydrogenase deficiencies were used. The throughput for one bench-top gas chromatography/mass spectrometry instrument is 20 samples per day. Thus, this method affords an accurate, rapid, noninvasive means for the differential diagnosis of CAH in the newborn period without the need for invasive testing and ACTH stimulation.

Genotype-phenotype analysis in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency.

CONTEXT: P450 oxidoreductase deficiency (PORD) is a unique congenital adrenal hyperplasia variant that manifests with glucocorticoid deficiency, disordered sex development (DSD), and skeletal malformations. No comprehensive data on genotype-phenotype correlations in Caucasian patients are available. OBJECTIVE: The objective of the study was to establish genotype-phenotype correlations in a large PORD cohort. DESIGN: The design of the study was the clinical, biochemical, and genetic assessment including multiplex ligation-dependent probe amplification (MLPA) in 30 PORD patients from 11 countries. RESULTS: We identified 23 P450 oxidoreductase (POR) mutations (14 novel) including an exonic deletion and a partial duplication detected by MLPA. Only 22% of unrelated patients carried homozygous POR mutations. p.A287P was the most common mutation (43% of unrelated alleles); no other hot spot was identified. Urinary steroid profiling showed characteristic PORD metabolomes with variable impairment of 17α-hydroxylase and 21-hydroxylase. Short cosyntropin testing revealed adrenal insufficiency in 89%. DSD was present in 15 of 18 46,XX and seven of 12 46,XY individuals. Homozygosity for p.A287P was invariably associated with 46,XX DSD but normal genitalia in 46,XY individuals. The majority of patients with mild to moderate skeletal malformations, assessed by a novel scoring system, were compound heterozygous for missense mutations, whereas nearly all patients with severe malformations carried a major loss-of-function defect on one of the affected alleles. CONCLUSIONS: We report clinical, biochemical, and genetic findings in a large PORD cohort and show that MLPA is a useful addition to POR mutation analysis. Homozygosity for the most frequent mutation in Caucasians, p.A287P, allows for prediction of genital phenotype and moderate malformations. Adrenal insufficiency is frequent, easily overlooked, but readily detected by cosyntropin testing.

Pubertal presentation in seven patients with congenital adrenal hyperplasia due to P450 oxidoreductase deficiency.

CONTEXT: P450 oxidoreductase (POR) is a crucial electron donor to all microsomal P450 cytochrome (CYP) enzymes including 17α-hydroxylase (CYP17A1), 21-hydroxylase (CYP21A2) and P450 aromatase. Mutant POR causes congenital adrenal hyperplasia with combined glucocorticoid and sex steroid deficiency. P450 oxidoreductase deficiency (ORD) commonly presents neonatally, with disordered sex development in both sexes, skeletal malformations, and glucocorticoid deficiency. OBJECTIVE: The aim of the study was to describe the clinical and biochemical characteristics of ORD during puberty. DESIGN: Clinical, biochemical, and genetic assessment of seven ORD patients (five females, two males) presenting during puberty was conducted. RESULTS: Predominant findings in females were incomplete pubertal development (four of five) and large ovarian cysts (five of five) prone to spontaneous rupture, in some only resolving after combined treatment with estrogen/progestin, GnRH superagonists, and glucocorticoids. Pubertal development in the two boys was more mildly affected, with some spontaneous progression. Urinary steroid profiling revealed combined CYP17A1 and CYP21A2 deficiencies indicative of ORD in all patients; all but one failed to mount an appropriate cortisol response to ACTH stimulation indicative of adrenal insufficiency. Diagnosis of ORD was confirmed by direct sequencing, demonstrating disease-causing POR mutations. CONCLUSION: Delayed and disordered puberty can be the first sign leading to a diagnosis of ORD. Appropriate testosterone production during puberty in affected boys but manifest primary hypogonadism in girls with ORD may indicate that testicular steroidogenesis is less dependent on POR than adrenal and ovarian steroidogenesis. Ovarian cysts in pubertal girls may be driven not only by high gonadotropins but possibly also by impaired CYP51A1-mediated production of meiosis-activating sterols due to mutant POR.

Concomitant mutations in the P450 oxidoreductase and androgen receptor genes presenting with 46,XY disordered sex development and androgenization at adrenarche.

CONTEXT: Undervirilization in males, i.e. 46,XY disordered sex development (46,XY DSD), is commonly caused by either lack of androgen action due to mutant androgen receptor (AR) or deficient androgen synthesis, e.g. due to mutations in 17alpha-hydroxylase (CYP17A1). Like all other microsomal cytochrome P450 (CYP) enzymes, CYP17A1 requires electron transfer from P450 oxidoreductase (POR). OBJECTIVE: The objective of the study was to analyze the clinical and biochemical phenotype in a 46,XY individual carrying concomitant POR and AR mutations and to dissect their impact on phenotypic expression. METHODS: We characterized the clinical and biochemical phenotype, genetic identification, and functional analysis of POR missense mutation by yeast micrososomal coexpression assays for CYP17A1, CYP21A2 and CYP19A1 activities. RESULTS: The patient presented neonatally with 46,XY DSD and was diagnosed as partial androgen insensitivity syndrome carrying a disease causing AR mutation (p.Q798E). She was raised as a girl and gonadectomized at the age of 4 yr. At 9 yr progressive clitoral enlargement prompted reassessment. Urinary steroid analysis was indicative of POR deficiency, but surprisingly androgen production was normal. Genetic analysis identified compound heterozygous POR mutations (p.601fsX12/p.Y607C). In vitro analysis confirmed p.Y607C as a pathogenic mutation with differential inhibition of steroidogenic CYP enzymes. CONCLUSION: Both mutant AR and POR are likely to contribute to the neonatal presentation with 46,XY DSD. Virilization at the time of adrenarche appears to suggest an age-dependent, diminishing disruptive effect of both mutant proteins. This case further highlights the importance to assess both gonadal and adrenal function in patients with 46,XY DSD.

11beta-hydroxysteroid dehydrogenase type 1 deficiency ('apparent cortisone reductase deficiency') in a 6-year-old boy.

OBJECTIVE: We present the 1st case of prepubertal hyperandrogenism because of a defect in the conversion of cortisone (E) to cortisol (F) by hepatic 11beta-hydroxysteroid dehydrogenase type 1. METHODS AND RESULTS: Clinical and anthropometric data were obtained. Serum androgens and gonadotropins with luteinizing hormone releasing hormone stimulation test, dexamethasone suppression test, and corticotropin-releasing hormone stimulation test were evaluated. Adrenal imaging and urinary steroid profiling by gas chromatography/mass spectrometry were employed. A 6.9-year-old boy presented with precocious pubarche, height (+2.6 SD), accelerated bone age (11.5 years), and Tanner stage 2 pubic hair and genitalia. Serum androgen levels were elevated and dexamethasone suppressible. Serum F was normal, but the E concentration was increased. Central precocious puberty and congenital adrenal hyperplasia were excluded. The excretion of androgen metabolites was moderately increased, but a highly increased tetrahydrocortisone (THE) and a diminished tetrahydrocortisol (THF + allo-THF) excretion was found with a [THF + allo-THF/ THE] ratio of 0.032 (normal controls 1.05 +/- 0.17). The corticotropin-releasing hormone stimulation test showed an exaggerated adrenocorticotropic hormone response, suggesting a relative deficiency of F. Two months of hydrocortisone treatment (17.5 mg daily) failed to suppress androgens adequately. Treatment with dexamethasone (0.375 mg/daily) resulted in androgen suppression. CONCLUSIONS: In the case of precocious pubarche and accelerated growth, the diagnosis of 11beta-hydroxysteroid dehydrogenase type 1 deficiency ('apparent cortisone reductase deficiency') should be considered. The diagnosis is based on determinations of urinary steroid metabolites.

Biochemical diagnosis of Antley-Bixler syndrome by steroid analysis.

Antley-Bixler syndrome (ABS, MIM 207410) is a skeletal abnormality syndrome primarily affecting head and limbs. Little is known of the origin of the condition but inactivating mutations in the fibroblast growth factor receptor (FGFR2) has been found in some patients. Genital ambiguity is seen occasionally in this condition, suggesting possible disordered steroidogenesis in early pregnancy. We report the steroid excretion of eight patients diagnosed with the syndrome and one with a related condition, a mild phenotype of the disorder since skeletal and genital abnormalities were not evident. The steroid excretion pattern was consistent and very distinctive in all nine patients. Metabolites of the two primary precursors of steroid hormones, pregnenolone and progesterone, were elevated as were the classical diagnostic metabolites for 17- and 21-hydroxylase deficiencies. Cortisol production was typically within the normal range but generally had blunted response to ACTH. Androgen metabolite excretion tends to be low in patients over 2 months of age, but may be elevated in the newborn period. The metabolome suggested attenuated steroid hydroxylation (including 17,20-lyase activity) although underlying cause is yet to be established. Mutations in CYP17 and CYP21 have not been found and currently the prime suspect is an abnormality in an essential redox partner (P450 oxidoreductase). This paper proposes use of the distinctive steroid metabolome as the primary biochemical parameter for diagnosis of ABS, at least the form not associated with FGFR2 mutations.