P450c17 deficiency in Brazilian patients: biochemical diagnosis through progesterone levels confirmed by CYP17 genotyping

46,XY DSD due to impaired androgen production

Disorders of androgen production can occur in all steps of testosterone biosynthesis and secretion carried out by the foetal Leydig cells as well as in the conversion of testosterone into dihydrotestosterone (DHT). The differentiation of Leydig cells from mesenchymal cells is the first walk for testosterone production. In 46,XY disorders of sex development (DSDs) due to Leydig cell hypoplasia, there is a failure in intrauterine and postnatal virilisation due to the paucity of interstitial Leydig cells to secrete testosterone. Enzymatic defects which impair the normal synthesis of testosterone from cholesterol and the conversion of testosterone to its active metabolite DHT are other causes of DSD due to impaired androgen production. Mutations in the genes that codify the enzymes acting in the steps from cholesterol to DHT have been identified in affected patients. Patients with 46,XY DSD secondary to defects in androgen production show a variable phenotype, strongly depending of the specific mutated gene. Often, these conditions are detected at birth due to the ambiguity of external genitalia but, in several patients, the extremely undervirilised genitalia postpone the diagnosis until late childhood or even adulthood. These patients should receive long-term care provided by multidisciplinary teams with experience in this clinical management.

Plasma corticosteroid profiling: brief opinion of its current status in clinical diagnosis and research

Adrenal steroid biosynthesis comprises a series of dynamically interrelated, enzyme-catalyzed reactions in two separate compartments, the zona glomerulosa and the zona fasciculata/reticularis. End products (cortisol, aldosterone and androgens), together with a proportion of the intermediate compounds, appear in the circulation as a characteristic profile. Rare deficiencies of individual enzymes modify this profile in a recognizable way. Previous exhaustive profiling suggests that their diagnosis can now often be made on the basis of single-compound analyses with concomitant genetic tests. However, high-capacity liquid chromatography coupled with tandem mass spectrometry-based methods are facilitating profiling of large population samples, revealing that smaller differences in enzyme efficiency, indicated by potentially more complex corticosteroid patterns, may be related to clinical wellbeing in a much larger proportion of the population.

Diagnosis of diseases of steroid hormone production, metabolism and action

Biochemical tests have been the basis for investigations of disorders affecting steroid hormones. In recent years it has been possible however to study the genes that determine functional enzymes, cofactors, receptors, transcription factors and signaling systems that are involved in the process. Analyses of mutations are available as a diagnostic service for only a few of these genes although research laboratories may be able to provide a service. Both biochemical and genetic research have brought to light new disorders. Some genes for transcription factors involved in the development of the endocrine organs have also been identified and patients with defects in these processes have been found. This paper will review general aspects of adrenal disorders with emphasis on clinical and laboratory findings. As with all endocrine investigations there are few single measurements that provide a definitive answer to a diagnosis. Timing of samples in relation to age, gender and time of day needs to be considered.

Genotyping of a Chinese family with 46,XX and 46,XY 17-hydroxylase deficiency

BACKGROUND

17-Hydroxylase deficiency is a rare form of congenital adrenal hyperplasia caused by CYP17A1 gene mutations.

METHOD

A 46,XY and a 46,XX Chinese patients with 17-hydroxylase deficiency in a family and their four generations family members were genotyped by PCR-sequencing method.

RESULTS

Two CYP17 gene mutations were identified from these patients. Among them, IVS1-1G > A was a novel splicing mutation which disrupted the acceptor signal of exon 2 and might create a new exon after exon 1. The indel mutation of TAC329AA was a one-base deletion mutation and one-base change at codon 329 in exon 6.

CONCLUSION

The results confirmed the diagnosis of 17-hydroxylase deficiency in these two patients and their autosome recessive heritage mode. The TAC329AA indel mutation had been identified in several reports of Chinese and Asian, suggesting that codon 329 was an unstable point of the CYP17 gene and this mutation was a prevalent CYP17 mutation in the Asian population. Although the noval mutation IVS1-1G > A founded in this family need more study to know its machinism of interrupting P450c17 function.

Genome-wide association study identifies eight loci associated with blood pressure

Elevated blood pressure is a common, heritable cause of cardiovascular disease worldwide. To date, identification of common genetic variants influencing blood pressure has proven challenging. We tested 2.5 million genotyped and imputed SNPs for association with systolic and diastolic blood pressure in 34,433 subjects of European ancestry from the Global BPgen consortium and followed up findings with direct genotyping (N ≤ 71,225 European ancestry, N ≤ 12,889 Indian Asian ancestry) and in silico comparison (CHARGE consortium, N = 29,136). We identified association between systolic or diastolic blood pressure and common variants in eight regions near the CYP17A1 (P = 7 × 10(-24)), CYP1A2 (P = 1 × 10(-23)), FGF5 (P = 1 × 10(-21)), SH2B3 (P = 3 × 10(-18)), MTHFR (P = 2 × 10(-13)), c10orf107 (P = 1 × 10(-9)), ZNF652 (P = 5 × 10(-9)) and PLCD3 (P = 1 × 10(-8)) genes. All variants associated with continuous blood pressure were associated with dichotomous hypertension. These associations between common variants and blood pressure and hypertension offer mechanistic insights into the regulation of blood pressure and may point to novel targets for interventions to prevent cardiovascular disease.

46,XY disorders of sex development (DSD)

The term disorders of sex development (DSD) includes congenital conditions in which development of chromosomal, gonadal or anatomical sex is atypical. Mutations in genes present in X, Y or autosomal chromosomes can cause abnormalities of testis determination or disorders of sex differentiation leading to 46,XY DSD. Detailed clinical phenotypes allow the identification of new factors that can alter the expression or function of mutated proteins helping to understand new undisclosed biochemical pathways. In this review we present an update on 46,XY DSD aetiology, diagnosis and treatment based on extensive review of the literature and our three decades of experience with these patients.

Loss of cytochrome P450 17A1 protein expression in a 17alpha-hydroxylase/17,20-lyase-deficient 46,XY female caused by two novel mutations in the CYP17A1 gene

17alpha-Hydroxylase deficiency (17OHD) is a rare form of congenital adrenal hyperplasia caused by mutations in the CYP17A1 gene. This condition shows considerable clinical and biochemical variation. Molecular characterization of novel mutations in the CYP17A1 gene and detailed study of their structural, enzymatic, and clinical consequences are required to fully understand enzyme behavior. Here, we present the first molecular characterization of two novel mutations in CYP17A1 in a 15-year-old female Mexican mestizo 46,XY female with primary amenorrhea and lack of pubertal development and severe hypertension that manifested only after surgery. A complete clinical and biochemical evaluation was compatible with 17OHD. Structural anomalies in the CYP17A1 gene were discovered by direct automated sequencing, which revealed a novel compound heterozygous K110X/R362H mutation that leads to a complete lack of enzyme activity. Immunohistochemical analyses performed to determine protein expression and localization showed that cytochrome P450 17A1 was completely absent in the patient's testicular tissue. Studies of novel mutations, such as those described here, provide important information that allows us to better understand the effect of a given mutation on enzyme function and to observe the impact of the mutation on clinical phenotype.

Combined 17 alpha-hydroxylase/17,20-lyase deficiency due to a homozygous 25 BP duplication (NT 4157-4181) at exon 5 in the CYP17 resulting in a premature stop codon predicted by molecular modeling

Combined 17alpha-hydroxylase/17,20-lyase deficiency is a rare, autosomal recessive form of congenital adrenal hyperplasia characterized by the coexistence of hypertension, caused by the hyperproduction of mineralocorticoid precursors and DSD in males and sexual infantilism in females, due to impaired production of sex hormones. Several CYP17 mutations resulting in 17alpha-hydroxylase/17,20-lyase deficiency have been reported previously. In the present study, we described a novel CYP17 mutation in two Brazilian sisters with primary amenorrhea, 46,XY karyotype, high basal levels of progesterone (3.4-4.9 ng/mL) and hypokalemic hypertension born to consanguineous parents. After PCR and automatic sequencing of CYP17 coding region, 25 bp duplication at exon 5 was found in the patients. This duplication started at codon 318 resulting in a premature stop codon at position 320 resulting in an ineffective and truncated protein and in accordance with the molecular modeling of P450c17. Therefore we expanded the repertoire of CYP17 mutations describing the largest duplication found in this gene in both sisters, with a clinical phenotype of combined 17alpha-hydroxylase/17,20-lyase deficiency and emphasizes the importance of the P450c 17 molecular modeling to predict the functional effect of these mutations.

Novel mutation in cytochrome P450c17 causes complete combined 17alpha-hydroxylase/17,20-lyase deficiency

BACKGROUND

Cytochrome P450c17 (CYP17) has two principal enzyme activities, 17alpha-hydroxylase and 17,20-lyase, which are required for cortisol and androgen biosynthesis, respectively. Mutations in the gene encoding for CYP17 result in 17alpha-hydroxylase deficiency (17OHD), a rare form of congenital adrenal hyperplasia, a disorder characterized by adrenal insufficiency, hypertension, primary amenorrhea and sexual infantilism. We describe a case of complete combined 17OHD caused by mutations in the CYP17 gene.

PATIENT

This study evaluates a 19 year-old Korean female born from a non-consanguineous relationship who presented with primary amenorrhea, hypertension, hyperpigmentation, absent axillary hair and pubic hair, and Tanner I breasts. Laboratory evaluation showed markedly elevated adrenocorticotropin and 11-deoxycorticosterone with suppressed plasma renin, aldosterone, and cortisol, consistent with 17OHD.

METHODS

Genomic DNA was isolated from peripheral blood leukocytes. The eight exons of the human CYP17 gene were amplified in four segments by polymerase chain reaction. Amplicons were gel-purified and directly sequenced.

RESULTS

The patient was found to be compound heterozygous for mutations in exon 6: a novel mutation R358X (CGA--TGA) and Y329 del/ sub (TAC-->AA). Both alterations introduce premature stop codons prior to the hemebinding cysteine and are predicted to completely inactivate the encoded P450c17 proteins.

CONCLUSION

This patient is a compound heterozygote for nonsense mutations in the CYP17 gene, which confirms the diagnosis of 17OHD.

Congenital adrenal hyperplasia: focus on the molecular basis of 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) is an autosomal recessive disorder caused by defects in one of several steroidogenic enzymes involved in the synthesis of cortisol from cholesterol in the adrenal glands. More than 90% of cases are caused by 21-hydroxylase deficiency, and the severity of the resulting clinical symptoms varies according to the level of 21-hydroxylase activity. 21-Hydroxylase deficiency is usually caused by mutations in theCYP21A2gene, which is located on the RCCX module, a chromosomal region highly prone to genetic recombination events that can result in a wide variety of complex rearrangements, such as gene duplications, gross deletions and gene conversions of variable extensions. Molecular genotyping ofCYP21A2and the RCCX module has proved useful for a more accurate diagnosis of the disease, and prenatal diagnosis. This article summarises the clinical features of 21-hydroxylase deficiency, explains current understanding of the disease at the molecular level, and highlights recent developments, particularly in diagnosis.

P450c17 deficiency: clinical and molecular characterization of six patients

CONTEXT

The characteristics of P450c17 deficiency include 46,XY disorder of sex development, hypertension, hypokalemia, and lack of pubertal development.

OBJECTIVE

To better understand this rare enzymatic deficiency, we analyzed the CYP17A1 gene in six affected patients.

DESIGN AND PATIENTS

We examined six patients, five 46,XY, and one 46,XX (age 9-29 yr) with complete lack of masculinization (female infantile external genitalia, no uterus) and delayed puberty, respectively, and different degrees of hypertension.

MAIN OUTCOME MEASUREMENTS

Genotype-phenotype correlation was measured.

RESULTS

Four homozygote mutations were identified by direct sequencing of the CYP17A1 gene corresponding to an alanin 302-proline (A302P) exchange; the loss of lysine 327 (K327del); the deletion of glutamate 331 (E331del); and the replacement of arginine 416 with a histidine (R416H). Both P450c17 activities were abolished in all the mutant proteins, except one, when expressed in COS1 cells. The E331del-mutated P450c17 retained 17alpha-hydroxylase activity. The mutant proteins were normally expressed, suggesting that the loss of enzymatic activity is not due to defects of synthesis, stability, or localization of P450c17 proteins.

CONCLUSION

These studies confirm lack of masculinization in 46,XY individuals as the pathognomic sign of the complete P450c17 deficiency. In XX individuals P450c17 deficiency should be considered in cases of delayed puberty. Age of onset and the severity of hypertension do not seem to be constant. Careful examination of long-term follow-ups in two of our patients suggested to us that estrogen treatment in P450c17-deficient patients might worsen the enzymatic defect, leading to aggravation of the hypertension.

17-Hydroxyprogesterone deficiency as a cause of sexual infantilism and arterial hypertension: laboratory and molecular diagnosis--a case report

The differential diagnosis of hypertension associated with hypokalemia in infancy and adolescence should necessarily include deficiency of the 17alpha-hydroxylase enzyme, a rare form of congenital adrenal hyperplasia (CAH). In addition to hypertension, the classic syndrome caused by this deficiency is characterized by suppressed production of sex hormones and consequently sexual infantilism. Although rare (1% of all forms of CAH), there appears to be a higher incidence of this syndrome in some population groups. This is a case report on two sisters followed up at the Department of Obstetrics and Gynecology, School of Medicine, Universidade Estadual de Campinas (UNICAMP), who were both found to have the 46,XY genotype with homozygosis for W406R, exon 7 of the CYP17 gene (OMIM 202110). The condition was diagnosed only at puberty when hypergonadotropic hypogonadism resulted in sexual infantilism; however, arterial hypertension had been present since infancy and late diagnosis and lack of timely adequate treatment resulted in complications.

Monogenic forms of low-renin hypertension

Hypertension is an important public health problem affecting more than 50 million individuals in the US alone. The most common form, essential hypertension, results from the complex interplay between genetic predisposition and environmental influences. In contrast, monogenic (mendelian) forms of hypertension are caused by single gene mutations that are influenced little, if at all, by environmental factors. Most monogenic forms of hypertension affect either electrolyte transport in the distal nephron, or the synthesis or activity of mineralocorticoid hormones, leading to the common pathogenic mechanisms of increased distal tubular reabsorption of sodium and chloride, volume expansion and hypertension. In young patients with a family history of hypertension who present with severe or refractory hypertension and characteristic hormonal and biochemical abnormalities, the differential diagnosis should include monogenic forms of hypertension. Genetic testing, which is increasingly available, can facilitate timely diagnosis and treatment of these relatively uncommon disorders, such that the underlying defect can be corrected or ameliorated and the long-term consequences of poorly controlled hypertension prevented.

Genotyping of five chinese patients with 17alpha-hydroxylase deficiency diagnosed through high-performance liquid chromatography serum adrenal profile: identification of two novel CYP17 mutations

CONTEXT

17alpha-Hydroxylase deficiency is a rare form of congenital adrenal hyperplasia caused by CYP17 gene mutations.

OBJECTIVE

Five Chinese patients with 17alpha-hydroxylase deficiency were genotyped.

PATIENTS

The five patients derived from four families living in Shandong Province, China. The diagnosis of 17alpha-hydroxylase deficiency was initially established through HPLC serum adrenal profiles in Qilu Hospital, China, from 1983-1993.

RESULTS

Three CYP17 gene mutations were identified from these patients. Among them, V311fs and Y329fs are two novel frame-shifting mutations. V311fs is an 8-bp nucleotide (TTAAATGG) deletion in exon 5. Y329fs is a deletion-insertion combined mutation (TAC-->AA) at codon 329 in exon 6. Two homozygotes for Y329fs and one compound heterozygote for Y329fs and V311fs were identified from three different families. Two homozygous sisters for the D487_S488_F489 deletion were identified.

CONCLUSION

The results confirmed the diagnostic value of the HPLC serum adrenal profile for 17alpha-hydroxylase deficiency. The D487_S488_F489 deletion had been identified in two previously genotyped Chinese families. In our present study, a third Chinese family with this mutation was identified, suggesting that this mutation is a prevalent CYP17 mutation in the Chinese population. The identification of Y329fs mutation in addition to three previously identified mutations at codon 329 suggests that codon 329 is an unstable point of the CYP17 gene. The mutations identified from our five patients appear to be random, but the recurrence of the Y329fs mutation may be attributed to a founder effect. Our studies suggest that 17alpha-hydroxylase deficiency may not be rare in the Chinese population.

Seventeen alpha-hydroxylase deficiency

Seventeen alpha-hydroxylase deficiency (17OHD) is a rare form of congenital adrenal hyperplasia in which defects in the biosynthesis of cortisol and sex steroid result in mineralocorticoid excess, hypokalemic hypertension and sexual abnormalities such as pseudohermaphroditism in males, and sexual infantilism in females. The disease is inherited in an autosomal recessive pattern, and is caused by mutations in the gene encoding cytochrome P450c17 (CYP17), which is the single polypeptide that mediates both 17alpha-hydroxylase and 17,20-lyase activities. We report the case of a 15-year-old patient with 17OHD who had a female phenotype but male karyotype (46,XY). The diagnosis was made based on classical clinical features, biochemical data and molecular genetic study. Two mutations were identified by polymerase chain reaction amplification and sequencing, including a S106P point mutation in exon 2 and a 9-bp (GACTCTTTC) deletion from nucleotide position 1519 in exon 8 of CYP17. The first of these mutations was found in the father and the second in the mother, and both have been previously reported in Asia. The patient's hypertension and hypokalemia resolved after glucocorticoid replacement and treatment with potassium-sparing diuretics. Sex hormone replacement was prescribed for induction of sexual development and reduction of the final height. Prophylactic gonadectomy was scheduled. In summary, 17OHD should be suspected in patients with hypokalemic hypertension and lack of secondary sexual development so that appropriate therapy can be implemented.

Gene expression changes induced in the testis by transplacental exposure to high and low doses of 17{alpha}-ethynyl estradiol, genistein, or bisphenol A

The purpose of this study was to determine (1) the transcriptional program elicited by exposure to three estrogen receptor (ER) agonists: 17 alpha-ethynyl estradiol (EE), genistein (Ges), and bisphenol A (BPA) during fetal development of the rat testis and epididymis; and (2) whether very low dosages of estrogens (evaluated over five orders of magnitude of dosage) produce unexpected changes in gene expression (i.e., a non-monotonic dose-response curve). In three independently conducted experiments, Sprague-Dawley rats were dosed (sc) with 0.001-10 microg EE/kg/day, 0.001-100 mg Ges/kg/day, or 0.002-400 mg BPA/kg/day. While morphological changes in the developing reproductive system were not observed, the gene expression profile of target tissues were modified in a dose-responsive manner. Independent dose-response analyses of the three studies identified 59 genes that are significantly modified by EE, 23 genes by Ges, and 15 genes by BPA (out of 8740), by at least 1.5 fold (up- or down-regulated). Even more genes were observed to be significantly changed when only the high dose is compared with all lower doses: 141, 46, and 67 genes, respectively. Global analyses aimed at detecting genes consistently modified by all of the chemicals identified 50 genes whose expression changed in the same direction across the three chemicals. The dose-response curve for gene expression changes was monotonic for each chemical, with both the number of genes significantly changed and the magnitude of change, for each gene, decreasing with decreasing dose. Using the available annotation of the gene expression changes induced by ER-agonist, our data suggest that a variety of cellular pathways are affected by estrogen exposure. These results indicate that gene expression data are diagnostic of mode of action and, if they are evaluated in the context of traditional toxicological end-points, can be used to elucidate dose-response characteristics.

CYP17 genotype predicts serum hormone levels among pre-menopausal women

BACKGROUND

CYP17, which encodes cytochrome P450c17alpha, mediates both steroid 17alpha-hydroxylase and 17,20-lyase activities, and is essential for the production of glucocorticoids and sex steroids. There is evidence that a common polymorphism in CYP17 (T27C) is associated with estrogen levels, making it a potential marker of disease risk.

METHODS

This is the first study to examine the relationship between CYP17 and estradiol (E2) using serum sampled exclusively from the early follicular phase of the menstrual cycle. We assessed the relationship between CYP17 and serum hormone levels, menstrual cycle length, bleed length, and age at menarche in 164 pre-menopausal women.

RESULTS

Among women with body mass index (BMI) < or =25 kg/m2, those with the TC and CC genotypes had 19 and 42% higher E2 (P for trend 0.007) and 14 and 30% higher dehydroepiandrosterone sulphate respectively (P for trend 0.10) than women with the TT genotype. Androstenedione levels did not differ between genotypes. Among women with BMI >25 kg/m2, hormone levels did not differ by genotype. Women with the C allele were also more likely to have menstrual cycle lengths <27 days [odds ratio (OR) for TC=2.36, 95% confidence interval (CI)=1.24-4.52; OR for CC=5.59, 95% CI=1.53-20.43 compared to TT]. CYP17 genotype was not associated with menstrual bleed length or age at menarche.

CONCLUSION

The CYP17 T27C polymorphism may be a marker of endocrine function.

Progesterone: the forgotten hormone in men?

'Classical' genomic progesterone receptors appear relatively late in phylogenesis, i.e. it is only in birds and mammals that they are detectable. In the different species, they mediate manifold effects regarding the differentiation of target organ functions, mainly in the reproductive system. Surprisingly, we know little about the physiology, endocrinology, and pharmacology of progesterone and progestins in male gender or men respectively, despite the fact that, as to progesterone secretion and serum progesterone levels, there are no great quantitative differences between men and women (at least outside the luteal phase). In a prospective cohort study of 1026 men with and without cardiovascular disease, we were not able to demonstrate any age-dependent change in serum progesterone concentrations. Progesterone influences spermiogenesis, sperm capacitation/acrosome reaction and testosterone biosynthesis in the Leydig cells. Other progesterone effects in men include those on the central nervous system (CNS) (mainly mediated by 5alpha-reduced progesterone metabolites as so-called neurosteroids), including blocking of gonadotropin secretion, sleep improvement, and effects on tumors in the CNS (meningioma, fibroma), as well as effects on the immune system, cardiovascular system, kidney function, adipose tissue, behavior, and respiratory system. A progestin may stimulate weight gain and appetite in men as well as in women. The detection of progesterone receptor isoforms would have a highly diagnostic value in prostate pathology (benign prostatic hypertrophy and prostate cancer). The modulation of progesterone effects on typical male targets is connected with a great pharmacodynamic variability. The reason for this is that, in men, some important effects of progesterone are mediated non-genomically through different molecular biological modes of action. Therefore, the precise therapeutic manipulation of progesterone actions in the male requires completely new endocrine-pharmacological approaches.