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Cytochrome P450 oxidoreductase deficiency (PORD) is a rare form of congenital adrenal hyperplasia that can manifest with skeletal malformations, ambiguous genitalia, and menstrual disorders caused by cytochrome P450 oxidoreductase (POR) mutations affecting electron transfer to all microsomal cytochrome P450 and some non-P450 enzymes involved in cholesterol, sterol, and drug metabolism. With the advancement of molecular biology and medical genetics, increasing numbers of PORD cases were reported, and the clinical spectrum of PORD was extended with studies on underlying mechanisms of phenotype-genotype correlations and optimum treatment. However, diagnostic challenges and management dilemma still exists because of unawareness of the condition, the overlapping manifestations with other disorders, and no clear guidelines for treatment. Delayed diagnosis and management may result in improper sex assignment, loss of reproductive capacity because of surgical removal of ruptured ovarian macro-cysts, and life-threatening conditions such as airway obstruction and adrenal crisis. The clinical outcomes and prognosis, which are influenced by specific POR mutations, the presence of additional genetic or environmental factors, and management, include early death due to developmental malformations or adrenal crisis, bilateral oophorectomies after spontaneous rupture of ovarian macro-cysts, genital ambiguity, abnormal pubertal development, and nearly normal phenotype with successful pregnancy outcomes by assisted reproduction. Thus, timely diagnosis including prenatal diagnosis with invasive and non-invasive techniques and appropriate management is essential to improve patients' outcomes. However, even in cases with conclusive diagnosis, comprehensive assessment is needed to avoid severe complications, such as chromosomal test to help sex assignment and evaluation of adrenal function to detect partial adrenal insufficiency. In recent years, it has been noted that proper hormone replacement therapy can lead to decrease or resolve of ovarian macro-cysts, and healthy babies can be delivered by in vitro fertilization and frozen embryo transfer following adequate control of multiple hormonal imbalances. Treatment may be complicated with adverse effects on drug metabolism caused by POR mutations. Unique challenges occur in female PORD patients such as ovarian macro-cysts prone to spontaneous rupture, masculinized genitalia without progression after birth, more frequently affected pubertal development, and impaired fertility. Thus, this review focuses only on 46, XX PORD patients to summarize the potential molecular pathogenesis, differential diagnosis of classic and non-classic PORD, and tailoring therapy to maintain health, avoid severe complications, and promote fertility., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang and Tian.)

Objective: To raise awareness of Cytochrome P450 Oxidoreductase Deficiency (PORD, a rare form of congenital adrenal hyperplasia (CAH), through a case of pregnant woman with virilization symptoms., Case Description: A 30-year-old Chinese woman was referred to hospital after 7 years of presenting signs of virilization, including voice deepening, acromegaly, hirsutism, clitoromegaly, and acne. These symptoms appeared since her third gestation. Her second birth died 9 hours after birth and had signs of clitoris hypertrophy. Her third born was a son who presented with flat nose, radius and humerus bone malformation, and small penis at birth. Panel of POR-related genetic tests revealed that the patient carried c.1370 G>A (p.R457H), which is a POR heterozygous gene, while her husband carried a POR heterozygous gene as well, c.1379 C>A (p.S460Y). Two heterozygous mutations of the POR were found in her son: c.1370 G>A and c.1379 C>A. In PORD, c.1370 G>A (p.R457H) was reported as a susceptible gene, while c.1379 C>A (p.S460Y) has not been reported as responsible for the disease so far., Discussion and Literature Review: PORD is a rare form of CAH and caused by POR gene mutations. Most PORD patients are identified and diagnosed in pediatrics department. Internal medicine and obstetrics physicians are unfamiliar with the disease. As clinical manifestations are diverse, PORD could be easy to miss or to be misdiagnosed. Typical clinical manifestation includes adrenal insufficiency-related symptoms, such as bone malformations and sexual development disorders. PORD is diagnosed through genetic testing. Investigations of steroid metabolic products in urine through gas chromatography-mass spectrometry or liquid chromatography-mass spectrometry are also helpful for the diagnosis, but neither of them are widely available in China. In this case, the patient had a history of infertility, and her third child was born with congenital defect and carried a PORD-related gene. In general clinical practice, if a pregnant woman presents with abnormal virilization symptoms, CAH possibilities should be considered, including rare causes such as PORD., Conclusion: PORD is a rare autosomal recessive genetic disease. We summarised the clinical characteristics and genotypes that were previously reported in the Chinese population and identified a novel mutation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhang, Woo, Hai, Wang, Lin, Huang, Peng, Wu, Zhang, Yan and Li.)

Cytochrome P450 oxidoreductase (POR) is a membrane-bound flavoprotein that helps in transferring electrons from its NADPH domain to all cytochrome P450 (CYP450) enzymes. Mutations in the POR gene could severely affect the metabolism of steroid hormones and the development of skeletal muscles, a condition known as Cytochrome P450 oxidoreductase deficiency (PORD). PORD is associated with clinical presentations of disorders of sex development, Antley and Bixler's syndrome (ABS), as well as an abnormal steroid hormone profile. We have performed an in silico analysis of POR 3D X-ray protein crystal structure to study the effects of reported mutations on the POR enzyme structure. A total of 32 missense mutations were identified, from 170 PORD patients, and mapped on the 3D crystal structure of the POR enzyme. In addition, five of the missense mutations (R457H, A287P, D210G, Y181D and Y607C) were further selected for an in-depth in silico analysis to correlate the observed changes in POR protein structure with the clinical phenotypes observed in PORD patients. Overall, missense mutations found in the binding sites of POR cofactors could lead to a severe form of PORD, emphasizing the importance of POR cofactor binding domains in transferring electrons to the CYP450 enzyme family.

Recent work has found increasing evidence of mitigated, incompletely penetrant phenotypes in heterozygous carriers of recessive Mendelian disease variants. We leveraged whole-exome imputation within the full UK Biobank cohort (n ∼ 500K) to extend such analyses to 3,475 rare variants curated from ClinVar and OMIM. Testing these variants for association with 58 quantitative traits yielded 102 significant associations involving variants previously implicated in 34 different diseases. Notable examples included a POR missense variant implicated in Antley-Bixler syndrome that associated with a 1.76 (SE 0.27) cm increase in height and an ABCA3 missense variant implicated in interstitial lung disease that associated with reduced FEV1/FVC ratio. Association analyses with 1,134 disease traits yielded five additional variant-disease associations. We also observed contrasting levels of recessiveness between two more-common, classical Mendelian diseases. Carriers of cystic fibrosis variants exhibited increased risk of several mitigated disease phenotypes, whereas carriers of spinal muscular atrophy alleles showed no evidence of altered phenotypes. Incomplete penetrance of cystic fibrosis carrier phenotypes did not appear to be mediated by common allelic variation on the functional haplotype. Our results show that many disease-associated recessive variants can produce mitigated phenotypes in heterozygous carriers and motivate further work exploring penetrance mechanisms., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Introduction: P450 oxidoreductase (POR) deficiency is a rare form of congenital adrenal hyperplasia. In both genders, it can lead to ambiguous genitalia, impaired steroidogenesis, and skeletal findings similar to those of Antley-Bixler syndrome., Cases: We describe two cases of POR deficiency. The first case was an 8.5-year-old girl who was admitted to our clinic due to ambiguous genitalia. Karyotype was 46, XX. There were mild dysmorphic facial findings and mild metacarpophalangeal joint deformity. The patient's basal cortisol and ACTH levels were normal, while 17-hydroxyprogesterone (17OHP) levels were high. Peak cortisol response to the ACTH stimulation test was found to be insufficient. Our second case, a sibling of the first case, was admitted for routine checkup at the age of 15 months. As in our first case, there were dysmorphic facial findings and metacarpophalangeal joint deformity. The genital structure was normal. Karyotype was 46, XY. Basal cortisol and ACTH levels were normal, while 17OHP level was slightly high. Peak cortisol response to the ACTH stimulation test was found to be insufficient. Based on our findings, POR deficiency was considered in both of these cases and NM_000941.3:c.929_937delTCTCGGACT(p.Ile310_Ser313delinsThr) (homozygous) mutation was detected in the POR gene that had not previously been described., Conclusion: We detected a novel variant in the POR gene in two sibling cases with adrenal insufficiency, dysmorphic face, and mild skeletal findings. While the detected mutation caused ambiguous genitalia in the female case, it did not cause ambiguous genitalia in the male case.

Objective: To characterize the clinical features of a female with P450 oxidoreductase (POR) deficiency and to investigate the underlying mechanisms of POR inactivation., Methods: The proband was a 35-year-old woman with primary infertility and menstrual irregularity. The reproductive endocrine profile was evaluated. DNA sequencing was conducted for the identification of POR gene mutation. RT-PCR was performed to confirm the impact of the mutation on POR mRNA. A molecular model was built for the structural analysis of mutant POR protein., Results: The evaluation of reproductive endocrine profile revealed elevation of serum follicle-stimulating hormone (11.48 mIU/ml), progesterone (11.00 ng/ml), 17α-hydroxyprogesterone (24.24 nmol/l), dehydroepiandrosterone (6300 nmol/l), and androstenedione (3.89 nmol/l) and decreased estradiol (36.02 pg/ml). Sequencing of the POR gene showed the female was a compound heterozygote of the paternal P399_E401 deletion and a novel maternal IVS14-1G>C mutation. Functional analysis revealed IVS14-1G>C mutation caused alternative splicing of POR mRNA, with the loss of 12 nucleotides in exon 15 (c.1898_1909delGTCTACGTCCAG). Also, the resulting mutant POR protein had a V603_Q606 deletion, which inactivated the nucleotide-binding domain of NADPH in POR protein (K602_Q606)., Conclusion: The mutation IVS14-1G>C of the POR gene could cause alternative splicing of POR mRNA and dysfunction of the resulting POR protein. Under proper IVF strategy with glucocorticoid therapy and endometrial preparation, females with mild POR deficiency still have the opportunity to have a live birth.

Objective: To explore the clinical features and molecular basis of a Chinese pedigree with two siblings affected by cytochrome P450 oxidoreductase deficiency (PORD)., Methods: Clinical features of the patients were reviewed, and their genomic DNA was subjected to next generation sequencing (NGS)., Results: The two siblings presented peculiar facies, genital hypoplasia and skeletal deformity. NGS revealed that both have carried compound heterozygous variants of the POR gene, namely c.1370G>A and c.517-19_517-10delGGCCCCTGTGinsC, which were respectively inherited from their parents., Conclusion: Both siblings were diagnosed with PORD based on sequencing of the POR gene. The newly discovered POR c.517-19_517-10delGGCCCCTGTGinsC has enriched the spectrum of PORD-related genetic variants.

Pediatric care providers, pediatricians, pediatric subspecialty physicians, and other health care providers should be able to recognize children with abnormal head shapes that occur as a result of both synostotic and deformational processes. The purpose of this clinical report is to review the characteristic head shape changes, as well as secondary craniofacial characteristics, that occur in the setting of the various primary craniosynostoses and deformations. As an introduction, the physiology and genetics of skull growth as well as the pathophysiology underlying craniosynostosis are reviewed. This is followed by a description of each type of primary craniosynostosis (metopic, unicoronal, bicoronal, sagittal, lambdoid, and frontosphenoidal) and their resultant head shape changes, with an emphasis on differentiating conditions that require surgical correction from those (bathrocephaly, deformational plagiocephaly/brachycephaly, and neonatal intensive care unit-associated skill deformation, known as NICUcephaly) that do not. The report ends with a brief discussion of microcephaly as it relates to craniosynostosis as well as fontanelle closure. The intent is to improve pediatric care providers' recognition and timely referral for craniosynostosis and their differentiation of synostotic from deformational and other nonoperative head shape changes., Competing Interests: This document is copyrighted and is property of the American Academy of Pediatrics and its Board of Directors. All authors have filed conflict of interest statements with the American Academy of Pediatrics. Any conflicts have been resolved through a process approved by the Board of Directors. The American Academy of Pediatrics has neither solicited nor accepted any commercial involvement in the development of the content of this publication. POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2020 by the American Academy of Pediatrics.)

Context: P450 oxidoreductase deficiency (PORD) is a rare genetic disorder that is associated with significant morbidity. However there has been limited analysis of reported PORD cases., Objective: To determine, based on the cohort of reported PORD cases, genotype-phenotype relationships for skeletal malformations, maternal virilisation in pregnancy, adrenal insufficiency, and disorders of sexual development (DSD)., Data Sources: PubMed and Web of Science from January 2004 to February 2018., Study Selection: Published case reports/series of patients with PORD. Eligible patients were unique, had biallelic mutations, and their clinical features were reported., Data Extraction: Patient data were manually extracted from the text of case reports/series. A malformation score, representing the severity of skeletal malformations, was calculated for each patient., Data Synthesis: Of the 211 patients published in the literature, 90 were eligible for inclusion. More than 60 unique mutations were identified in this cohort. Four groups of mutations were identified, through regression modeling, as having significantly different skeletal malformation scores. Maternal virilization in pregnancy, reported for 21% of patients, was most common for R457H mutations. Adrenal insufficiency occurred for the majority of patients (78%) and was typically mild, with homozygous R457H mutations being the least deficient. DSD affected most patients (72%), but were less common for males (46XY) with homozygous R457H mutations., Conclusions: PORD is a complex disorder with many possible mutations affecting a large number of enzymes. By analyzing the cohort of reported PORD cases, this study identified clear relationships between genotype and several important phenotypic features., (© Endocrine Society 2019. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Antley-Bixler syndrome (ABS) caused by P450 oxidoreductase deficiency (PORD) is a congenital adrenal hyperplasia with skeletal malformations and disordered sex development in both sexes. There have been no reports of ABS caused by PORD in Chinese children., Methods: We described the clinical and genetic characteristics of eight Chinese children with ABS caused by PORD and compared them with those of subjects in previous studies., Results: Eight patients, aged 6 months-17.8 years, showed strikingly similar craniofacial malformations. We first described four unreported features: lower eyelid fat pads (4/8), prominent lower eyelid-zygoma transverse line (4/8), underdeveloped or absent antihelix (5/8) and single earlobe crease (5/8). Five 46, XY patients presented various degrees of undervirilization, while three 46, XX cases showed masculinization. Basal endocrine measurements revealed the following consistent results: normal cortisol; elevated adrenocorticotropic hormone, progesterone, pregnenolone, 17-hydroxypropgesterone, and corticosterone; and decreased or normal testosterone/oestradiol. We identified three previously reported variants and four novel variants (c.51719_51710delGGCCCCTGTGinsC, p.D210G, p.Y248X and p.R554X) of POR. The most prevalent variant was p.R457H (8/16). The hydrocortisone dosages of patients differed because of variable degrees of adrenal insufficiency., Conclusions: We described novel phenotypes and genotypes of ABS caused by PORD. The variant p.R457H was the most prevalent in this cohort. All subjects had combined characteristics of 17-hydroxylase and 21-hydroxylase deficiency. Steroid replacement therapy for patients with PORD requires individually tailored dosing.

Androgen biosynthesis in the human fetus proceeds through the adrenal sex steroid precursor dehydroepiandrosterone, which is converted to testosterone in the gonads, followed by further activation to 5α-dihydrotestosterone in genital skin, thereby facilitating male external genital differentiation. Congenital adrenal hyperplasia due to P450 oxidoreductase deficiency results in disrupted dehydroepiandrosterone biosynthesis, explaining undervirilization in affected boys. However, many affected girls are born virilized, despite low circulating androgens. We hypothesized that this is due to a prenatally active, alternative androgen biosynthesis pathway from 17α-hydroxyprogesterone to 5α-dihydrotestosterone, which bypasses dehydroepiandrosterone and testosterone, with increased activity in congenital adrenal hyperplasia variants associated with 17α-hydroxyprogesterone accumulation. Here we employ explant cultures of human fetal organs (adrenals, gonads, genital skin) from the major period of sexual differentiation and show that alternative pathway androgen biosynthesis is active in the fetus, as assessed by liquid chromatography-tandem mass spectrometry. We found androgen receptor expression in male and female genital skin using immunohistochemistry and demonstrated that both 5α-dihydrotestosterone and adrenal explant culture supernatant induce nuclear translocation of the androgen receptor in female genital skin primary cultures. Analyzing urinary steroid excretion by gas chromatography-mass spectrometry, we show that neonates with P450 oxidoreductase deficiency produce androgens through the alternative androgen pathway during the first weeks of life. We provide quantitative in vitro evidence that the corresponding P450 oxidoreductase mutations predominantly support alternative pathway androgen biosynthesis. These results indicate a key role of alternative pathway androgen biosynthesis in the prenatal virilization of girls affected by congenital adrenal hyperplasia due to P450 oxidoreductase deficiency., Competing Interests: The authors declare no competing interest., (Copyright © 2019 the Author(s). Published by PNAS.)

Objective: To explore the genetic basis for a child affected with multiple malformations., Methods: Genomic DNA was extracted from peripheral blood samples from the child and her parents. Tro whole exome sequencing and bioinformatics analysis were carried out. Suspicted mutations were verified by PCR and Sanger sequencing., Results: The patient, a 2-year-old girl, presented with multiple malformations including dysmorphism, skeletal malformations and ambigulous genitalia. Through genetic testing, she was diagnosed with Antley-Bixler syndrome caused by compound heterozygous mutations of the POR gene (c.919G>T and c.1615G>A), which were derived from her mother and father, respectively., Conclusion: The compound heterozygous mutations of the POR gene probably underlie the Antley-Bixler syndrome in this patient.

The term linkeropathies (LKs) refers to a group of rare heritable connective tissue disorders, characterized by a variable degree of short stature, skeletal dysplasia, joint laxity, cutaneous anomalies, dysmorphism, heart malformation, and developmental delay. The LK genes encode for enzymes that add glycosaminoglycan chains onto proteoglycans via a common tetrasaccharide linker region. Biallelic variants in XYLT1 and XYLT2, encoding xylosyltransferases, are associated with Desbuquois dysplasia type 2 and spondylo-ocular syndrome, respectively. Defects in B4GALT7 and B3GALT6, encoding galactosyltransferases, lead to spondylodysplastic Ehlers-Danlos syndrome (spEDS). Mutations in B3GAT3, encoding a glucuronyltransferase, were described in 25 patients from 12 families with variable phenotypes resembling Larsen, Antley-Bixler, Shprintzen-Goldberg, and Geroderma osteodysplastica syndromes. Herein, we report on a 13-year-old girl with a clinical presentation suggestive of spEDS, according to the 2017 EDS nosology, in whom compound heterozygosity for two B3GAT3 likely pathogenic variants was identified. We review the spectrum of B3GAT3-related disorders and provide a comparison of all LK patients reported up to now, highlighting that LKs are a phenotypic continuum bridging EDS and skeletal disorders, hence offering future nosologic perspectives., Competing Interests: All authors declare that there are no conflicts of interest concerning this work.

Antley-Bixler syndrome (ABS) is a rare childhood disorder affecting skeletal development. Some patients may also have genital anomalies and impaired steroidogenesis. Diagnostic criteria for ABS has not been fully established, though craniosynostosis, midface hypoplasia and elbow synostosis are minimum requirements. The etiology of ABS is complex, which included autosomal dominant form caused by FGFR2 gene mutations, autosomal recessive form caused by POR gene mutations, and high oral dose of fluconazole during pregnancy. Patients may die from dyspnea due to upper respiratory tract obstruction. This review summarizes research progress on the clinical features, etiology, differential diagnosis, treatment and prevention of ABS.

Although POR deficiency (PORD) is assumed to be accompanied by excessive placental androgen accumulation and enhanced adrenal and testicular androgen production via the backdoor pathway as well as compromised testicular androgen production via the frontdoor pathway, there is no direct evidence for the flux of excessive placental androgens into the fetal circulation and for the production of dihydrotestosterone (DHT) via the backdoor pathway. We examined longitudinal serum and urine steroid metabolite profiles in a 46,XY infant with PORD who was prenatally identified because of the progressive fetal masculinization and maternal virilization from the mid-gestation and the presence of fetal radio-humeral synostosis and was confirmed to have compound heterozygous mutations of POR (p.Q201X and p.R457H). The results showed (1) markedly and inappropriately elevated serum androstenedione and testosterone (T) values at birth, (2) a markedly increased serum DHT value with a normal DHT/T ratio at birth, (3) transient elevation of serum T and DHT values accompanied by a normal DHT/T ratio and concomitant elevations of intermediate steroid metabolites on both the frontdoor and backdoor pathways at 30 days of age, and (4) persistent PORD-compatible urine steroid profiles. Although the data obtained from a single infantile patient are too premature to be generalized, they imply: (1) the transfer of excessive placental androgens into the fetal as well as the maternal circulations from the mid-gestation, (2) lack of a clinically discernible amount of DHT production via the adrenal backdoor pathway around birth, and (3) the activation of both the frontdoor and backdoor pathways in the testis around the mini-puberty, with no production of a clinically discernible amount of DHT via the testicular backdoor pathway., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Cytochrome P450 oxidoreductase deficiency (PORD) is a rare disease exhibiting a variety of clinical manifestations. It can be difficult to differentiate with other diseases such as 21-hydroxylase deficiency (21-OHD), polycystic ovary syndrome (PCOS) and Antley-Bixler syndrome (ABS). Nearly 100 cases of PORD have been reported worldwide. However, the genetic characters and clinical management are still unclear, especially in China., Case Presentation: In this study, we report a 27-year-old female Chinese patient who first presented with amenorrhea and recurrence of large ovary cyst. She was misdiagnosed with PCOS and non-classical 21-OHD due to ovary cysts and elevated 17-hydroxy-progesterone. The patient's complaining of a mild difficulty of bending the metacarpophalangeal joints reminded us to consider PORD, which usually presents with skeletal deformities and sexual dysfunction. The diagnosis of PORD was confirmed by genetic analyses, which showed the patient harboring a homozygous missense mutation in the POR gene (R457H) and her parents carrying the heterozygous mutation. The patient was treated with low-dose corticosteroids and estrogen/progesterone sequential therapy, and her ovarian cyst gradually reduced with regular menstruation in the follow-up. Moreover, the clinical and genetic characteristics of 104 previously reported PORD cases were also summarized and analyzed., Conclusions: PORD is a very rare disease which can be easily misdiagnosed in mild cases. Clinicians should keep in mind of this disease in patients with sexual dysfunction, especially combined with special skeletal deformities. Our data could provide a consciously understanding of this disease for clinic practicers. Low-dose corticosteroids combined with estrogen/progesterone sequential therapy will be effective in PORD patients with recurrence of large ovary cyst. The fact that the reported PORD patients in China carrying an identical variant R457H in POR gene also give us a viewpoint that R457H mutation in POR gene maybe important in causing PORD in Chinese as same as in Japanese.

Recently, a newly identified autosomal recessive skeletal dysplasia was described characterized by calvarial abnormalities (including cranium bifidum, coronal, and lambdoid synostosis), oligodactyly, femoral bowing, narrow thorax, small pelvic bones, and radiohumeral synostosis. In the two families described, a more severe phenotype led to in utero lethality in three siblings while in a single patient in a second family the phenotype was sufficiently mild to allow survival to 5 months of age. The disorder is caused by biallelic missense mutations in CYP26B1, which encodes for a cytochrome P450 enzyme responsible for the catabolism of retinoic acid in a temporally and spatially restricted fashion during embryonic development. Here, we provide the third family affected by the disorder and the first affected individual to survive beyond infancy. This woman homozygous for c.1303G>A; p.(Gly435Ser) in CYP26B1, which was associated with multisutural synostosis, radiohumeral synostosis, normal bone mineral density, and apparent intellectual disability, a phenotype with significant similarities to Antley-Bixler and Pfeiffer syndromes. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Human NADPH-cytochrome P450 oxidoreductase (POR) gene mutations are associated with severe skeletal deformities and disordered steroidogenesis. The human POR mutation A287P presents with disordered sexual development and skeletal malformations. Difficult recombinant expression and purification of this POR mutant suggested that the protein was less stable than WT. The activities of cytochrome P450 17A1, 19A1, and 21A2, critical in steroidogenesis, were similar using our purified, full-length, unmodified A287P or WT POR, as were those of several xenobiotic-metabolizing cytochromes P450, indicating that the A287P protein is functionally competent in vitro, despite its functionally deficient phenotypic behavior in vivo Differential scanning calorimetry and limited trypsinolysis studies revealed a relatively unstable A287P compared with WT protein, leading to the hypothesis that the syndrome observed in vivo results from altered POR protein stability. The crystal structures of the soluble domains of WT and A287P reveal only subtle differences between them, but these differences are consistent with the differential scanning calorimetry results as well as the differential susceptibility of A287P and WT observed with trypsinolysis. The relative in vivo stabilities of WT and A287P proteins were also examined in an osteoblast cell line by treatment with cycloheximide, a protein synthesis inhibitor, showing that the level of A287P protein post-inhibition is lower than WT and suggesting that A287P may be degraded at a higher rate. Current studies demonstrate that, unlike previously described mutations, A287P causes POR deficiency disorder due to conformational instability leading to proteolytic susceptibility in vivo, rather than through an inherent flavin-binding defect., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)

Background: Antley-Bixler syndrome (ABS) is an exceptionally rare craniosynostosis syndrome that can be accompanied by disordered steroidogenesis, and is mainly caused by mutations in the POR gene, inherited in an autosomal recessive manner. Here we report the prenatal and postmortem findings of three sibling fetuses with ABS as a result of compound heterozygosity of a paternal submicroscopic deletion and a maternal missense mutation in the POR gene., Methods: Prenatal ultrasound and postmortem examination were performed in three sibling fetuses with termination of pregnancy at 22, 23, and 17 weeks of gestation, respectively. Molecular analysis of fetus 2 and 3 included (a) bidirectional sequencing of exon 8 of the POR gene after amplification of the specific locus by polymerase chain reaction, to detect single nucleotide variants (SNVs) and (b) high resolution comparative genomic hybridization (CGH) positive single nucleotide polymorphism array CGH (aCGH) analysis to detect copy number variants (CNVs), copy neutral areas of loss of heterozygosity and uniparental disomy., Results: The diagnosis of ABS was suggested by the postmortem examination findings. The combination of the POR gene molecular analysis and aCGH revealed a compound heterozygous genotype of a maternal SNV (p.A287P) and a paternal CNV (NC_000007.13:g.(?_75608488)_(75615534_?)del)., Conclusion: To the best of our knowledge, these sibling fetuses add to the few reported cases of ABS, caused by a combination of a SNV and a CNV in the POR gene. The detailed description of the pathologic and radiographic findings of second trimester fetuses affected with ABS adds novel knowledge concerning the early ABS phenotype, in lack of previous relevant reports. Birth Defects Research (Part A) 106:536-541, 2016. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Fibroblast growth factor receptors (FGFRs) and FGF ligands are highly expressed in the developing kidney and lower urinary tract. Several classic studies showed many effects of exogenous FGF ligands on embryonic renal tissues in vitro and in vivo. Another older landmark publication showed that mice with a dominant negative Fgfr fragment had severe renal dysplasia. Together, these studies revealed the importance of FGFR signaling in kidney and lower urinary tract development. With the advent of modern gene targeting techniques, including conditional knockout approaches, several publications have revealed critical roles for FGFR signaling in many lineages of the kidney and lower urinary tract at different stages of development. FGFR signaling has been shown to be critical for early metanephric mesenchymal patterning, Wolffian duct patterning including induction of the ureteric bud, ureteric bud branching morphogenesis, nephron progenitor survival and nephrogenesis, and bladder mesenchyme patterning. FGFRs pattern these tissues by interacting with many other growth factor signaling pathways. Moreover, the many genetic Fgfr and Fgf animal models have structural defects mimicking numerous congenital anomalies of the kidney and urinary tract seen in humans. Finally, many studies have shown how FGFR signaling is critical for kidney and lower urinary tract patterning in humans.

Case Presentation: A 36-year old man, operated on for cryptorchidism at the age of 8 years, was referred to the Outpatient Clinic of Reproductive Endocrinology for investigation of infertility. Clinical examination revealed ambiguous genitalia: penis 4-5 cm, testicular volume 2-3 ml, hypospadias, hypertrophic foreskin and scrotum bifida. Mild hypertension was confirmed. No skeletal malformations were detected., Design: Hormonal and electrolytic determinations as well as semen analysis were conducted. PCR of the coding regions of 17-hydroxylase/17,20 lyase (P450c17) and of P450 oxidoreductase (POR) genes was also performed., Results: Normal levels of electrolytes, low levels of androgens, high levels of gonadotropins and 17-hydroxyprogesterone as well as azoospermia were detected. Karyotype was shown to be 46,XY. Both hCG and ACTH stimulation significantly increased 17-hydroxyprogesterone with no increase in androgens. The diagnosis was congenital adrenal hyperplasia with apparent combined P450c17 and P450c21 deficiency due to mutations in the POR gene. Sequencing of the POR gene revealed: one deletion in exon 12 (Del 1696_1698delGTC >del531Valine) and one missense mutation in exon 7 (A259G) as well as two polymorphisms: rs1057868 (C/T A503V) and rs1057870 (G/A S572S) in exons 12 and 13, respectively. No nucleotide changes were detected in the 8 exons of P450c17., Conclusions: Molecular findings were consistent with the diagnosis of P450 oxidoreductase deficiency. Despite this severe deficiency, skeletal malformations simulating Antley-Bixler syndrome, which usually characterize the most severe forms, were not confirmed. This discrepancy could be attributed to the differential impact of a POR variant on each one of the P450 enzymes.

Purpose: The authors report on a rare case of maternal virilization during pregnancy caused by autosomal recessive P450 oxidore- ductase (POR) deficiency., Materials and Methods: A 24-year-old primigravida developed a deepening voice and hirsutism in the second trimester. Prenatal ultrasonography failed to detect any fetal abnormality and fetal growth was normal. POR deficiency was suspected, but the mother declined fetal genetic testing. A female neonate was delivered by cesarean section at 41 weeks' gestation., Results: The neonate had skeletal abnormalities. Mutational analysis of the POR gene demonstrated homozygosity for c.1370 G>A and p.R457H in the patient and heterozygosity in her parents. POR deficiency was confirmed in the neonate., Conclusion: POR deficiency should be suspected in cases of maternal virilization. Maternal urinary estriol, fetal magnetic resonance imaging, and parental genetic testing should be performed. Parental consent for fetal genetic testing should be sought to ensure prompt diagnosis and early treatment.

Cholesterol plays a key role in many cellular processes, and is generated by cells through de novo biosynthesis or acquired from exogenous sources through the uptake of low-density lipoproteins. Cholesterol biosynthesis is a complex, multienzyme-catalyzed pathway involving a series of sequentially acting enzymes. Inherited defects in genes encoding cholesterol biosynthetic enzymes or other regulators of cholesterol homeostasis result in severe metabolic diseases, many of which are rare in the general population and currently without effective therapy. Historically, these diseases have been viewed as discrete disorders, each with its own genetic cause and distinct pathogenic cascades that lead to its specific clinical features. However, studies have recently shown that three of these diseases have an unanticipated mechanistic convergence. This surprising finding is not only shedding light on details of cellular cholesterol homeostasis but also suggesting novel approaches to therapy.

NADPH-cytochrome P450 oxidoreductase (POR) is the primary electron donor for cytochromes P450, dehydrocholesterol reductase, heme oxygenase, and squalene monooxygenase. Human patients with specific mutations in POR exhibit severe developmental malformations including disordered steroidogenesis, sexual ambiguities and various bone defects, similar to those seen in patients with Antley-Bixler syndrome (ABS). To probe the role of POR during bone development, we generated a conditional knockout mouse (CKO) by cross breeding Por (lox/lox) and Dermo1 Cre mice. CKO mice were smaller than their littermate controls and exhibited significant craniofacial and long bone abnormalities. Differential staining of the CKO mice skull bases shows premature fusion of the sphenooccipital and basioccipital-exoccipital synchondroses. Class III malocclusion was noted in adult knockout mice with an unusual overgrowth of the lower incisors. Shorter long bones were observed along with a reduction in the bone volume fraction, measured by microCT, in the Por-deleted mice compared to age- and sex-matched littermate controls. Concerted up- or down-regulation of proteins in the FGF signaling pathway observed by immunohistochemistry in the tibia samples of CKO mice compared to wild type controls shows a decrease in the FGF signaling pathway. To our knowledge, this is the first report of a mouse model that recapitulates both skull and long bone defects upon Por deletion, offering an approach to study the sequelae of POR mutations. This unique model demonstrates that P450 metabolism in bone itself is potentially important for proper bone development, and that an apparent link exists between the POR and FGF signaling pathways, begging the question of how an oxidation-reduction flavoprotein affects developmental and cellular signaling processes.

We report the first known case of p450 oxidoreductase deficiency (PORD) in a Spanish boy who presented ambiguous genitalia at birth as a unique feature. He had palpable gonads in the inguinal canal and a normal 46,XY karyotype. Blood tests showed increased lanosterol and androgen precursors (17-OH-pregnenolone and 17-OH-progesterone) and low adrenal androgens (dehydroepiandrosterone and its sulfate). Blood pressure and serum electrolytes were normal. As he had low-testosterone response to human chorionic gonadotropin stimulation but responded to exogenous testosterone with phallic growth, male sex was assigned. Testosterone/dihydrotestosterone ratio and inhibin B were normal. Adrenal insufficiency was detected by corticotropin test. Hydrocortisone replacement treatment was administered. Congenital adrenal hyperplasia was ruled out and molecular analysis of POR gene showed the missense mutation p.Gly539Arg in compound heterozygosity located at splice acceptor site of intron 2 and the coding variant p.Gly80Arg. Surgery for cryptorchidism and hypospadias was performed.

Cytochrome P450 oxidoreductase (POR) is an enzyme that is essential for multiple metabolic processes, chiefly among them are reactions catalyzed by cytochrome P450 proteins for metabolism of steroid hormones, drugs and xenobiotics. Mutations in POR cause a complex set of disorders that often resemble defects in steroid metabolizing enzymes 17α-hydroxylase, 21-hydroxylase and aromatase. Since our initial reports of POR mutations in 2004, more than 200 different mutations and polymorphisms in POR gene have been identified. Several missense variations in POR have been tested for their effect on activities of multiple steroid and drug metabolizing P450 proteins. Mutations in POR may have variable effects on different P450 partner proteins depending on the location of the mutation. The POR mutations that disrupt the binding of co-factors have negative impact on all partner proteins, while mutations causing subtle structural changes may lead to altered interaction with specific partner proteins and the overall effect may be different for each partner. This review summarizes the recent discoveries related to mutations and polymorphisms in POR and discusses these mutations in the context of historical developments in the discovery and characterization of POR as an electron transfer protein. The review is focused on the structural, enzymatic and clinical implications of the mutations linked to newly identified disorders in humans, now categorized as POR deficiency., (Copyright © 2012 Elsevier Inc. All rights reserved.)

We review the current knowledge about the "backdoor" pathway for the biosynthesis of dihydrotestosterone (DHT). While DHT is produced from cholesterol through the conventional "frontdoor" pathway via testosterone, recent studies have provided compelling evidence for the presence of an alternative "backdoor" pathway to DHT without testosterone intermediacy. This backdoor pathway is known to exist in the tammar wallaby pouch young testis and the immature mouse testis, and has been suggested to be present in the human as well. Indeed, molecular analysis has identified pathologic mutations of genes involved in the backdoor pathway in genetic male patients with undermasculinized external genitalia, and urine steroid profile analysis has argued for the relevance of the activated backdoor pathway to abnormal virilization in genetic females with cytochrome P450 oxidoreductase deficiency and 21-hydroxylase deficiency. It is likely that the backdoor pathway is primarily operating in the fetal testis in a physiological condition to produce a sufficient amount of DHT for male sex development, and that the backdoor pathway is driven with a possible interaction between fetal and permanent adrenals in pathologic conditions with increased 17-hydroxyprogesterone levels. These findings provide novel insights into androgen biosynthesis in both physiological and pathological conditions., (Copyright © 2012 Wiley Periodicals, Inc., a Wiley company.)

Deficiency of the enzyme P450 oxidoreductase is a rare form of congenital adrenal hyperplasia with characteristics of combined and partial impairments in steroidogenic enzyme activities, as P450 oxidoreductase transfers electrons to CYP21A2, CYP17A1, and CYP19A1. It results in disorders of sex development and skeletal malformations similar to Antley-Bixley syndrome. We report the case of a 9-year-old girl who was born with virilized genitalia (Prader stage V), absence of palpable gonads, 46,XX karyotype, and hypergonadotropic hypogonadism. During the first year of life, ovarian cyst, partial adrenal insufficiency, and osteoarticular changes, such as mild craniosynostosis, carpal and tarsal synostosis, and limited forearm pronosupination were observed. Her mother presented severe virilization during pregnancy. The molecular analysis of P450 oxidoreductase gene revealed compound heterozygosis for the nonsense p.Arg223*, and the novel missense p.Met408Lys, inherited from the father and the mother, respectively.

Cytochrome P450 enzymes catalyze the biosynthesis of steroid hormones and metabolize drugs. There are seven human type I P450 enzymes in mitochondria and 50 type II enzymes in endoplasmic reticulum. Type II enzymes, including both drug-metabolizing and some steroidogenic enzymes, require electron donation from a two-flavin protein, P450 oxidoreductase (POR). Although knockout of the POR gene causes embryonic lethality in mice, we discovered human POR deficiency as a disorder of steroidogenesis associated with the Antley-Bixler skeletal malformation syndrome and found mild POR mutations in phenotypically normal adults with infertility. Assay results of mutant forms of POR using the traditional but nonphysiologic assay (reduction of cytochrome c) did not correlate with patient phenotypes; assays based on the 17,20 lyase activity of P450c17 (CYP17) correlated with clinical phenotypes. The POR sequence in 842 normal individuals revealed many polymorphisms; amino acid sequence variant A503V is encoded by ~28% of human alleles. POR A503V has about 60% of wild-type activity in assays with CYP17, CYP2D6, and CYP3A4, but nearly wild-type activity with P450c21, CYP1A2, and CYP2C19. Activity of a particular POR variant with one P450 enzyme will not predict its activity with another P450 enzyme: Each POR-P450 combination must be studied individually. Human POR transcription, initiated from an untranslated exon, is regulated by Smad3/4, thyroid receptors, and the transcription factor AP-2. A promoter polymorphism reduces transcription to 60% in liver cells and to 35% in adrenal cells. POR deficiency is a newly described disorder of steroidogenesis, and POR variants may account for some genetic variation in drug metabolism.

The present review describes the transgenic mouse models that have been designed to evaluate the functions of the cytochrome P450s involved in cholesterol and bile acid synthesis, as well as their link with disease. The knockout of cholesterogenic Cyp51 is embrionally lethal, with symptoms of Antley-Bixler syndrome occurring in mice, whereas the evidence for this association is conflicting in humans. Disruption of Cyp7a1 from classic bile acid synthesis in mice leads to either increased postnatal death or a milder phenotype with elevated serum cholesterol. The latter is similar to the case in humans, where CYP7A1 mutations associate with high plasma low-density lipoprotein and hepatic cholesterol content, as well as deficient bile acid excretion. Disruption of Cyp8b1 from an alternative bile acid pathway results in the absence of cholic acid and a reduced absorption of dietary lipids; however, the human CYP8B1 polymorphism fails to explain differences in bile acid composition. Unexpectedly, apparently normal Cyp27a1(-/-) mice still synthesize bile acids that originate from the compensatory pathway. In humans, CYP27A1 mutations cause cerebrotendinous xanthomatosis, suggesting that only mice can compensate for the loss of alternative bile acid synthesis. In line with this, Cyp7b1 knockouts are also apparently normal, whereas human CYP7B1 mutations lead to a congenital bile acid synthesis defect in children or spastic paraplegia in adults. Mouse knockouts of the brain-specific Cyp46a1 have reduced brain cholesterol excretion, whereas, in humans, CYP46A1 polymorphisms associate with cognitive impairment. At present, cytochrome P450 family 39 is poorly characterized. Despite important physiological differences between humans and mice, mouse models prove to be an invaluable tool for understanding the multifactorial facets of cholesterol and bile acid-related disorders., (© 2011 The Authors Journal compilation © 2011 FEBS.)

NADPH-cytochrome P450 oxidoreductase (CYPOR) variants have been described in patients with perturbed steroidogenesis and sexual differentiation, related to Antley-Bixler syndrome (ABS). It is important to determine the effect of these variants on CYP3A4, the major drug-metabolizing cytochrome P450 (P450) in humans. In this study, 12 CYPOR_ABS variants were separately coexpressed with CYP3A4 in a robust in vitro system to evaluate the effects of these variants on CYP3A4 activity in a milieu that recapitulates the stoichiometry of the mammalian systems. Full-length CYPOR variants were coexpressed with CYP3A4, resulting in relative expression levels comparable to those found in hepatic tissue. Dibenzylfluorescein (DBF), a CYP3A-specific reporter substrate (Biopharm Drug Dispos 24:375-384, 2003), was used to compare the variants and wild-type (WT) CYPOR activities with that of human liver microsomes. CYP3A4, combined with WT CYPOR, demonstrated kinetic parameters (k(cat) and K(m)) equal to those for pooled human liver microsomes. CYPOR variants Y181D, Y459H, V492E, L565P, and R616X all demonstrated maximal loss of CYP3A4 catalytic efficiency, whereas R457H and G539R retained ∼10 and 30% activities, respectively. Conversely, variants P228L, M263V, A287P, and G413S each showed WT-like capacity (k(cat)/K(m)), with the A287P variant being formerly reported to exhibit substantially lower catalytic efficiency. In addition, Q153R exhibited 60% of WT CYPOR capacity to support the DBF O-debenzylation reaction, contradicting increased catalytic efficiency (k(cat)/K(m)) relative to that for the WT, reported previously. Our data indicate the importance of use of simulated, validated in vitro systems, employing full-length proteins with appropriate stoichiometric incorporation of protein partners, when pharmacogenetic predictions are to be made for P450-mediated biotransformation.

Context: POR (cytochrome P450 oxidoreductase) is a ubiquitously expressed gene encoding an electron donor to all microsomal P450 enzymes and several non-P450 enzymes. POR mutations cause an autosomal recessive disorder characterized by skeletal dysplasia, adrenal dysfunction, and disorders of sex development. Although recent studies have indicated the presence of a CpG-rich region characteristic of housekeeping genes around the untranslated exon 1 (exon 1U) and a tropic effect of thyroid hormone on POR expression via thyroid hormone receptor-β, detailed regulatory mechanisms for the POR expression remain to be clarified., Objective: Our objective was to report a pivotal element of the proximal promoter of POR., Results: We first studied three patients (cases 1-3) with POR deficiency due to compound heterozygosity with an p.R457H mutation and transcription failure of an apparently normal allele, by oligoarray comparative genomic hybridization and serial direct sequencing of the deletion fusion points. Consequently, a 2,487-bp microdeletion involving exon 1U was identified in case 1 and an identical 49,604-bp deletion involving exon 1U and exon 1 was found in cases 2 and 3. We next analyzed the 2,487-bp region commonly deleted in cases 1-3 by in silico analysis, DNA binding analysis, luciferase assays, and methylation analysis. The results showed a critical function of the evolutionally conserved SP1 binding sites just upstream of exon 1U, especially the binding site at the position -26/-17, in the transcription of POR., Conclusions: The results suggest that the SP1 binding sites constitute an essential element of the POR proximal promoter.

Cytochrome P450 oxidoreductase (POR) deficiency is a recently discovered new variant of congenital adrenal hyperplasia. Distinctive features of POR deficiency are the presence of disorders of sexual development in both sexes, glucocorticoid deficiency and skeletal malformations similar to those observed in the Antley-Bixler syndrome.

This review describes the mouse knockout models of cholesterol synthesis, together with human malformations and drugs that target cholesterogenic enzymes. Generally, the sooner a gene acts in cholesterol synthesis, the earlier the phenotype occurs. Humans with loss of function of early cholesterogenic enzymes have not yet been described, and in the mouse, loss of Hmgcr is preimplantation lethal. Together, these results indicate that the widely prescribed cholesterol-lowering statins are potentially teratogenic. The Mvk knockout is early embryonic lethal in the mouse, the absence of Fdft1 is lethal at E9.5-12.5 dpc, while the Cyp51 knockouts die at 15.0 dpc. Fungal CYP51 inhibitor azoles are teratogenic in humans, potentially leading to symptoms of Antley-Bixler syndrome. The X-linked mutations in Nsdhl and Ebp are embryonic lethal in male mice, while heterozygous females are also affected. Consequently, the anticancer drugs, tamoxifen and toremifene, inhibiting human EBP, may be harmful in early pregnancy. The Dhcr7 and Dhcr24 knockout mice die shortly after birth, while humans survive with Smith-Lemli-Opitz syndrome or desmosterolosis. Since cholesterol is essential for hedgehog signaling, disturbance of this pathway by antipsychotics and -depressants explains some drug side effects. In conclusion, defects in cholesterol synthesis are generally lethal in mice, while humans with impaired later steps of the pathway can survive with severe malformations. Evidence shows that drugs targeting or, by coincidence, inhibiting human cholesterol synthesis are better avoided in early pregnancy. Since some drugs with teratogenic potential still stay on the market, this should be avoided in new cholesterol-related drug development.

Patients with P450 oxidoreductase (POR) deficiency typically present with adrenal insufficiency, genital anomalies and bony malformations resembling the Antley-Bixler craniosynostosis syndrome. Since our first report in 2004, more than 40 POR mutations have been identified in over 65 patients. POR is the obligate electron donor to all microsomal P450 enzymes, including the steroidogenic enzymes CYP17A1, CYP21A2 and CYP19A1. POR deficiency may cause disordered sexual development manifested as genital undervirilization in 46, XY newborns as well as overvirilization in those who are 46, XX. This may be explained by impaired aromatization of fetal androgens that may cause maternal virilization and low urinary estriol levels during pregnancy. In addition, the alternate 'backdoor' pathway of androgen biosynthesis, which leads to dihydrotestosterone production bypassing androstenedione and testosterone, may also play a role. Functional assays studying the effects of POR mutations on steroidogenesis showed that several POR variants impaired CYP17A1, CYP21A2 and CYP19A1 activities to different degrees, indicating that each POR variant must be studied separately for each potential target P450 enzyme. POR variants may also affect skeletal development and drug metabolism. As most drugs are metabolized by hepatic microsomal P450 enzymes, studies of the impact of POR mutations on drug-metabolizing P450s are particularly important., (Copyright © 2011 S. Karger AG, Basel.)

Objective: Patients with congenital adrenal hyperplasia due to P450 oxidoreductase (POR) deficiency (ORD) present with disordered sex development and glucocorticoid deficiency. This is due to disruption of electron transfer from mutant POR to microsomal cytochrome P450 (CYP) enzymes that play a key role in glucocorticoid and sex steroid synthesis. POR also transfers electrons to all major drug-metabolizing CYP enzymes, including CYP3A4 that inactivates glucocorticoid and oestrogens. However, whether ORD results in impairment of in vivo drug metabolism has never been studied., Design: We studied an adult patient with ORD due to homozygous POR A287P, the most frequent POR mutation in Caucasians, and her clinically unaffected, heterozygous mother. The patient had received standard dose oestrogen replacement from 17 until 37 years of age when it was stopped after she developed breast cancer., Methods: Both subjects underwent in vivo cocktail phenotyping comprising the oral administration of caffeine, tolbutamide, omeprazole, dextromethorphan hydrobromide and midazolam to assess the five major drug-metabolizing CYP enzymes. We also performed genotyping for variant CYP alleles known to affect drug metabolism., Results: Though CYP enzyme genotyping predicted normal or high enzymatic activities in both subjects, in vivo assessment showed subnormal activities of CYP1A2, CYP2C9, CYP2D6 and CYP3A4 in the patient and of CYP1A2 and CYP2C9 in her mother., Conclusions: Our results provide in vivo evidence for an important role of POR in regulating drug metabolism and detoxification. In patients with ORD, in vivo assessment of drug-metabolizing activities with subsequent tailoring of drug therapy and steroid replacement should be considered.

Cytochrome P450 3A4 (CYP3A4), the major P450 present in human liver metabolizes approximately half the drugs in clinical use and requires electrons supplied from NADPH through NADPH-P450 reductase (POR, CPR). Mutations in human POR cause a rare form of congenital adrenal hyperplasia from diminished activities of steroid metabolizing P450s. In this study we examined the effect of mutations in POR on CYP3A4 activity. We used purified preparations of wild type and mutant human POR and in vitro reconstitution with purified CYP3A4 to perform kinetic studies. We are reporting that mutations in POR identified in patients with disordered steroidogenesis/Antley-Bixler syndrome (ABS) may reduce CYP3A4 activity, potentially affecting drug metabolism in individuals carrying mutant POR alleles. POR mutants Y181D, A457H, Y459H, V492E and R616X had more than 99% loss of CYP3A4 activity, while POR mutations A287P, C569Y and V608F lost 60-85% activity. Loss of CYP3A4 activity may result in increased risk of drug toxicities and adverse drug reactions in patients with POR mutations., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Antley-Bixler syndrome (ABS) is an exceptionally rare craniosynostosis syndrome characterized by radiohumeral synostosis present from the perinatal period. There is a wide spectrum of anomalies seen within ABS, and other features include midface hypoplasia; choanal stenosis or atresia; multiple joint contractures; visceral anomalies, particularly of the genitourinary system; and impaired steroidogenesis. The condition of ABS is curious in that mutations of 2 separate genes have been identified and that there seem to be subtle phenotypic differences between the 2 genotypes. Mutations of the P450 oxidoreductase gene have been reported in those patients with genital anomalies and/or impaired steroidogenesis, and the S351C mutation of the fibroblast growth factor receptor 2 gene has been reported predominantly in those patients with normal genitalia and steroidogenesis. We report a series of 4 patients with ABS and review their main findings and management.

The 46,XX disorders of sex development (DSDs) cause virilisation or masculinisation of the female foetus. The final common pathway of all 46,XX DSDs is excess dihydrotestosterone (DHT) or potent foreign androgen in the genital tissue during the critical period of sexual differentiation. Whereas the foetal testis is source of androgen in the male, it is the foetal adrenal that produces the DHT precursors in the female. By understanding the principles of human steroid biosynthesis, the pathogenesis of each disorder may be logically deduced, and treatment strategies are rationally constructed. In practice, however, therapies for many of these diseases are fraught with complications and caveats, and current approaches leave much room for improvement. This review discusses these diseases, their pathogenesis and approaches to therapy. We emphasise areas where improved treatments are sorely needed., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

Cytochrome P450 oxidoreductase deficiency is a recently established autosomal recessive disease characterised by ambiguous genitalia, impaired steroidogenesis, and skeletal malformations, referred to as Antley-Bixler syndrome. Clinical manifestations in affected patients are highly variable. We report on a girl with P450 oxidoreductase deficiency who presented with virilisation at birth. There was transient maternal virilisation during pregnancy as well. She was initially diagnosed with congenital adrenal hyperplasia caused by 21-hydroxylase deficiency and/or aromatase deficiency. At 1 year of age, skeletal abnormalities suggestive of Antley-Bixler syndrome were detected. Molecular analysis of the fibroblast growth factor receptor 2 (FGFR2) gene was normal but POR gene analysis showed that she was homozygous for an R457H missense mutation. The diagnosis, P450 oxidoreductase deficiency, was confirmed. Results of her endocrine studies and urinary steroid profiling are also presented.

Antley-Bixler syndrome (ABS) is a skeletal malformation syndrome primarily affecting the skull and limbs. Although causal mutations in the FGFR2 gene have been found in some patients, mutations in the electron donor enzyme P450 oxidoreductase gene (POR) have recently been found to cause ABS in other patients. In addition to skeletal malformations, POR deficiency also causes glucocorticoid deficiency and congenital adrenal hyperplasia with ambiguous genitalia in both sexes. Here, we report on a 7-month-old Korean girl with ABS and ambiguous genitalia who was confirmed by POR gene analysis. Our patient showed typical skeletal findings with brachycephaly, mid-face hypoplasia, and radiohumeral synostosis. She also had partial labial fusion and a single urogenital orifice, as well as increased 17alpha-hydroxyprogesterone levels, suggesting a 21-hydroxylase deficiency. Cortisol and DHEA-sulfate response to rapid adrenocorticotropic hormone (ACTH) stimulation was inadequate. Direct sequencing of the POR gene revealed compound heterozygous mutations (I444fsX449 and R457H). This is the first report of a Korean patient with ABS caused by POR gene mutations.

Cytochrome P450 oxidoreductase (POR) is the obligate electron donor for all microsomal cytochrome P450 enzymes, which catalyze the metabolism of a wide spectrum of xenobiotic and endobiotic compounds. Point mutations in POR have been found recently in patients with Antley-Bixler-like syndrome, which includes limb skeletal defects. In order to study P450 function during limb and skeletal development, we deleted POR specifically in mouse limb bud mesenchyme. Forelimbs and hind limbs in conditional knockout (CKO) mice were short with thin skeletal elements and fused joints. POR deletion occurred earlier in forelimbs than in hind limbs, leading additionally to soft tissue syndactyly and loss of wrist elements and phalanges due to changes in growth, cell death, and skeletal segmentation. Transcriptional analysis of E12.5 mouse forelimb buds demonstrated the expression of P450s involved in retinoic acid, cholesterol, and arachidonic acid metabolism. Biochemical analysis of CKO limbs confirmed retinoic acid excess. In CKO limbs, expression of genes throughout the whole cholesterol biosynthetic pathway was upregulated, and cholesterol deficiency can explain most aspects of the phenotype. Thus, cellular POR-dependent cholesterol synthesis is essential during limb and skeletal development. Modulation of P450 activity could contribute to susceptibility of the embryo and developing organs to teratogenesis.

Akhenaten was one of Egypt's most controversial pharaohs, in part because of his strange appearance in images produced after he had declared Aten, the Sun-disc, his one-and-only god. Whether these were symbolic representations or realistic ones that indicate a deforming genetic disorder is the subject of continuing debate. The authors present evidence that the bizarre physical features portrayed in these images are not only realistic but were shared by many members of Egypt's 18th Dynasty. The features are best explained by either 2 different familial disorders-the aromatase excess syndrome and the sagittal craniosynostosis syndrome-or a variant of the Antley-Bixler syndrome caused by a novel mutation in one of the genes controlling the P450 enzymes, which regulate steroidogenesis and cranial bone formation.