Context 17α-Hydroxylase/17,20-lyase deficiency (17OHD) caused by mutations in the CYP17A1 gene is a rare form of congenital adrenal hyperplasia typically characterised by cortisol deficiency, mineralocorticoid excess and sex steroid deficiency. Objective To examine the phenotypic spectrum of 17OHD by clinical and biochemical assessment and corresponding in silico and in vitro functional analysis. Design Case series. Patients and results We assessed eight patients with 17OHD, including four with extreme 17OHD phenotypes: two siblings presented with failure to thrive in early infancy and two with isolated sex steroid deficiency and normal cortisol reserve. Diagnosis was established by mass spectrometry-based urinary steroid profiling and confirmed by genetic CYP17A1 analysis, revealing homozygous and compound heterozygous sequence variants. We found novel (p.Gly111Val, p.Ala398Glu, p.Ile371Thr) and previously described sequence variants (p.Pro409Leu, p.Arg347His, p.Gly436Arg, p.Phe53/54del, p.Tyr60IlefsLys88X). In vitro functional studies employing an overexpression system in HEK293 cells showed that 17,20-lyase activity was invariably decreased while mutant 17α-hydroxylase activity retained up to 14% of WT activity in the two patients with intact cortisol reserve. A ratio of urinary corticosterone over cortisol metabolites reflective of 17α-hydroxylase activity correlated well with clinical phenotype severity. Conclusion Our findings illustrate the broad phenotypic spectrum of 17OHD. Isolated sex steroid deficiency with normal stimulated cortisol has not been reported before. Attenuation of 17α-hydroxylase activity is readily detected by urinary steroid profiling and predicts phenotype severity. Significance statement Here we report, supported by careful phenotyping, genotyping and functional analysis, a prismatic case series of patients with congenital adrenal hyperplasia due to 17α-hydroxylase (CYP17A1) deficiency (17OHD). These range in severity from the abolition of function, presenting in early infancy, and unusually mild with isolated sex steroid deficiency but normal ACTH-stimulated cortisol in adult patients. These findings will guide improved diagnostic detection of CYP17A1 deficiency.

The broad phenotypic spectrum of 17α-hydroxylase/17,20-lyase (CYP17A1) deficiency: a case series.

Most steroidogenesis disorders are caused by mutations in genes encoding the steroidogenic enzymes, but work in the past 20 years has identified related disorders caused by mutations in the genes encoding the cofactors that transport electrons from NADPH to P450 enzymes. Most P450s are microsomal and require electron donation by P450 oxidoreductase (POR); by contrast, mitochondrial P450s require electron donation via ferredoxin reductase (FdxR) and ferredoxin (Fdx). POR deficiency is the most common and best-described of these new forms of congenital adrenal hyperplasia. Severe POR deficiency is characterized by the Antley-Bixler skeletal malformation syndrome and genital ambiguity in both sexes, and hence is easily recognized, but mild forms may present only with infertility and subtle disorders of steroidogenesis. The common POR polymorphism A503V reduces catalysis by P450c17 (17-hydroxylase/17,20-lyase) and the principal drugmetabolizing P450 enzymes. The 17,20-lyase activity of P450c17 requires the allosteric action of cytochrome b5, which promotes interaction of P450c17 with POR, with consequent electron transfer. Rare b5 mutations are one of several causes of 17,20-lyase deficiency. In addition to their roles with steroidogenic mitochondrial P450s, Fdx and FdxR participate in the synthesis of iron-sulfur clusters used by many enzymes. Disruptions in the assembly of Fe-S clusters is associated with Friedreich ataxia and Parkinson disease. Recent work has identified mutations in FdxR in patients with neuropathic hearing loss and visual impairment, somewhat resembling the global neurologic disorders seen with mitochondrial diseases. Impaired steroidogenesis is to be expected in such individuals, but this has not yet been studied.

/pdf/steroidogenic-electron-transfer-factors-and-their-diseases-2th918goup.pdf

Steroidogenic electron-transfer factors and their diseases.

Objective To study and describe the achievement of successful pregnancy and delivery in a patient with 17,20-lyase deficiency. Design Controlled ovarian stimulation (COS) and In Vitro fertilization (IVF), cryopreservation of embryos and frozen-thawed embryo transfer (ET). Setting IVF clinic. Patient A 24 years old, infertile patient with 17,20-lase deficiency. Interventions Controlled ovarian stimulation, follicular aspiration- egg retrieval, IVF, embryo cryopreservation, thawed ET. Main outcome measures Clinical pregnancy, successful delivery. Results Isolated 17,20-lyase deficiency is caused by mutations in the CYP17A1 gene (coding for cytochrome P450c17), POR (coding for cytochrome P450 oxidoreductase) and CYB5A (coding for microsomal cytochrome b5) genes. A 24 yo patient with 17,20-lyase deficiency had undergone IVF with gonadotropin releasing hormone agonist (GnRHa) protocol, prednisone, and gonadotropins. After human chorionic gonadotropin (hCG) trigger 37 oocytes were retrieved, 25 ova fertilized, and 17 embryos cryopreserved. After menstrual bleeding, the endometrium was stimulated with oral estradiol, under progesterone suppression with long acting GnRHa and prednisone. When endometrial width of 8.5 mm was reached, vaginal progesterone was added, while gradually decreasing prednisone. On the fourth day of progesterone supplement, two thawed embryos were transferred. After 11 days of human menopausal gonadotropin (hMG), estradiol concentration moderately increased, but progesterone levels remained high, therefore, no fresh ET was performed. Twelve days after thawed ET, hCG was positive, and seven days later, an intrauterine gestational sac was detected, but the pregnancy ended in missed abortion. After two months, another frozen-thawed embryo transfer (FET) was performed, generating a normal gestation, which ended in successful delivery. Conclusion Pregnancy can be achieved in patients with 17,20-lyase deficiency, by IVF, freezing all embrya, and ET in a subsequent cycle, while suppressing endogenous ovarian progesterone with a GnRHa and adrenal suppression with high dose glucocorticoids.

Successful Delivery in 17,20-Lyase Deficiency.

Comparative piRNAs Profiles Give a Clue to Transgenerational Inheritance of Sex-Biased piRNAs in Cynoglossus semilaevis

Objective The objective of this study was to report CYB5A deficiency, to discuss the contribution of steroid metabolomics to diagnosis and interpretation, and to highlight the presence of testicular microlithiasis. Methods Two siblings with ambiguous genitalia at birth were later found to carry novel CYB5A variants, with resulting isolated 17, 20 lyase deficiency. We compared urine steroid data obtained between birth and adulthood with that from other cases. Results Neonatal urine steroid profiles show a relative increase of 16-hydroxylated pregnenolone metabolites. Thereafter, there are no distinguishing features until puberty, when sex steroid deficiency drives gonadotrophin production, resulting in marked increases of 17-hydroxyprogesterone metabolites derived from the gonads. This excess may be revealed pre-pubertally by gonadotrophin stimulation testing. Novel findings are first, a considerable capacity for DHEA synthesis in the neonatal period compared to childhood and adulthood, suggesting that DHEAS production is much less dependent on CYB5A at birth; second, no consistent change in "backdoor pathway" intermediates; third, side chain cleavage of cortisol is largely unaffected, supporting the existence of a different lyase not dependent on CYB5A; fourth, increased 17-hydroxyprogesterone metabolites and very low androgen metabolites are diagnostic post-pubertally. Conclusion This is the fourth disease-causing variant in CYB5A in isolated 17, 20 lyase deficiency and the first associated with testicular microlithiasis. Establishing a biochemical diagnosis pre-pubertally should now be possible using urine steroid profiling, supported by synacthen and gonadotrophin stimulation testing. We recommend liquid chromatography-mass spectrometry/mass spectrometry rather than immunoassay for serum steroid analysis, early methaemoglobin measurement and surveillance should testicular microlithiasis be detected.

Isolated 17, 20 Lyase Deficiency Secondary to a Novel CYB5A Variant: Comparison of Steroid Metabolomic Findings with Published Cases Provides Diagnostic Guidelines and Greater Insight into Its Biological Role.

Isolated 17,20-lyase deficiency may be caused by mutations in the CYP17A1 (coding for cytochrome P450c17), POR (coding for cytochrome P450 oxidoreductase) and CYB5A (coding for microsomal cytochrome b5) genes. Of these, mutations in the CYB5A gene have thus far only been described in genetic males who presented with methemoglobinemia and 46,XY disorders of sex development (DSD) due to 17,20-lyase deficiency. A 24-year-old Chinese woman presented to the hematology outpatient clinic with purplish discoloration of fingers, toes, and lips since childhood. Investigations confirmed methemoglobinemia. A homozygous c.105C>G (p.Tyr35Ter) nonsense mutation was detected in the CYB5A gene. Hormonal studies showed isolated 17,20-lyase deficiency. Interestingly, she had a completely normal female phenotype with no DSD, normal pubertal development, and spontaneous pregnancy giving birth uneventfully to a healthy female infant. The sex hormone-related features of genetic females with 17,20-lyase deficiency due to cytochrome b5 gene mutation appear to differ from that of females with 17,20-lyase deficiency caused by other genetic defects who presented with hypergonadotropic hypogonadism and infertility and differ from genetic males with the same mutation.

/pdf/isolated-17-20-lyase-deficiency-in-a-cyb5a-mutated-female-2053bywbzy.pdf

Isolated 17,20-Lyase Deficiency in a CYB5A Mutated Female With Normal Sexual Development and Fertility.

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Isolated 17,20-Lyase Deficiency in a CYB5A Mutated Female With Normal Sexual Development and Fertility.