Molecular Basis of CYP19A1 Deficiency in a 46,XX Patient With R550W Mutation in POR: Expanding the PORD Phenotype

Exploring Novel Variants of the Cytochrome P450 Reductase Gene (POR) from the Genome Aggregation Database by Integrating Bioinformatic Tools and Functional Assays

Cytochrome P450 oxidoreductase (POR) is an essential redox partner for steroid and drug-metabolizing cytochromes P450 located in the endoplasmic reticulum. Mutations in POR lead to metabolic disorders, including congenital adrenal hyperplasia, and affect the metabolism of steroids, drugs, and xenobiotics. In this study, we examined approximately 450 missense variants of the POR gene listed in the Genome Aggregation Database (gnomAD) using eleven different in silico prediction tools. We found that 64 novel variants were consistently predicted to be disease-causing by most tools. To validate our findings, we conducted a population analysis and selected two variations in POR for further investigation. The human POR wild type and the R268W and L577P variants were expressed in bacteria and subjected to enzyme kinetic assays using a model substrate. We also examined the activities of several cytochrome P450 proteins in the presence of POR (WT or variants) by combining P450 and reductase proteins in liposomes. We observed a decrease in enzymatic activities (ranging from 35% to 85%) of key drug-metabolizing enzymes, supported by POR variants R288W and L577P compared to WT-POR. These results validate our approach of curating a vast amount of data from genome projects and provide an updated and reliable reference for diagnosing POR deficiency.

Diagnostic challenges and management advances in cytochrome P450 oxidoreductase deficiency, a rare form of congenital adrenal hyperplasia, with 46, XX karyotype

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.

Congenital adrenal hyperplasia, disorders of sex development, and infertility in patients with POR gene pathogenic variants: a systematic review of the literature

BACKGROUND

P450 oxidoreductase (POR) deficiency (PORD) is characterized by congenital adrenal hyperplasia (CAH) and disorders of sex development (DSD) in both sexes. PORD can also associate with skeletal defects. However, the prevalence of these phenotypes is unknown.

AIM

To evaluate the prevalence of CAH, DSD, and infertility of patients with POR gene pathogenic variants by a systematic review of the literature.

METHODS

The literature search was performed through PubMed, MEDLINE, Cochrane, Academic One Files, Google Scholar, and Scopus databases. All studies reporting information on CAH, DSD, testicular adrenal rest tumor (TARTs), and fertility in patients with POR gene pathogenic variants were included. Finally, the prevalence of abnormal phenotypes was calculated.

RESULTS

Of the 246 articles initially retrieved, only 48 were included for a total of 119 (46 males and 73 females) patients with PORD. We also included the case of a male patient who consulted us for CAH and TARTs but without DSD. This patient, found to be a carrier of combined heterozygous POR mutation, reached fatherhood spontaneously. All the patients found had CAH. The presence of DSD was found in 65.2%, 82.1%, and 82.1% of patients with compound heterozygosity, homozygosity, or monoallelic heterozygous variants, respectively. The prevalence was significantly higher in females than in males. The prevalence of TARTs in patients with PORD is 2.7%. Only 5 women with PORD became pregnant after assisted reproductive techniques and delivered a healthy baby. Except for the recently reported proband, no other studies focused on male infertility in patients with POR gene variants.

CONCLUSION

This systematic review of the literature reports the prevalence of CAH, DSD, and TARTs in patients with PORD. The unknown prevalence of POR gene pathogenetic variants and the paucity of studies investigating fertility do not allow us to establish whether PORD is associated with infertility. Further studies on both women and men are needed to clarify this relationship.

Study of differential proteomics in granulosa cells of premature ovarian insufficiency (POI) and the roles and mechanism of RAC1 in granulosa cells

In the present study, we focused on characterizing the proteome in granulosa cells in patients with biochemical premature ovarian insufficiency (bPOI) in order to identify differential proteins and investigate the fundamental mechanisms of POI. A total of 2688 proteins were identified based on the data-independent acquisition method, and 70 differentially expressed proteins were significant. Bioinformatic analyses, including gene expression pattern analysis, gene ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes pathway analysis, and Search Tool for the Retrieval of Interacting Genes/Proteins analysis, revealed discrete modules and the underlying molecular mechanisms in bPOI. Importantly, we observed that Ras-related C3 botulinum toxin substrate 1 (RAC1) was downregulated in the granulosa cells of bPOI. Low expression of RAC1 may affect the development process of POI by affecting the proliferation, apoptosis, and hormone synthesis of granulosa cells. Downregulation of RAC1 expression in the KGN and COV434 cells inhibited cell proliferation, blocked cells in the G1/G0 phase, and promoted apoptosis. Western blot results showed that β-catenin and cyclin D1 in the KGN and COV434 cells transfected with RAC1-siRNA were downregulated, while P21 and Bax were upregulated. Knocking down RAC1 in the KGN cells or adding the RAC1 enzyme inhibitor to the human luteinized granulosa cells (hLGC) inhibited the synthesis of E₂, and the expression of aromatase and follicle-stimulating hormone receptor (FSHR) was reduced.

Loss of Protein Stability and Function Caused by P228L Variation in NADPH-Cytochrome P450 Reductase Linked to Lower Testosterone Levels

Cytochrome P450 oxidoreductase (POR) is the redox partner of steroid and drug-metabolising cytochromes P450 located in the endoplasmic reticulum. Mutations in POR cause a broad range of metabolic disorders. The POR variant rs17853284 (P228L), identified by genome sequencing, has been linked to lower testosterone levels and reduced P450 activities. We expressed the POR wild type and the P228L variant in bacteria, purified the proteins, and performed protein stability and catalytic functional studies. Variant P228L affected the stability of the protein as evidenced by lower unfolding temperatures and higher sensitivity to urea denaturation. A significant decline in the rate of electron transfer to cytochrome c and thiazolyl blue tetrazolium (MTT) was observed with POR P228L, while activities of CYP3A4 were reduced by 25% and activities of CYP3A5 and CYP2C9 were reduced by more than 40% compared with WT POR. The 17,20 lyase activity of CYP17A1, responsible for the production of the main androgen precursor dehydroepiandrosterone, was reduced to 27% of WT in the presence of the P228L variant of POR. Based on in silico and in vitro studies, we predict that the change of proline to leucine may change the rigidity of the protein, causing conformational changes in POR, leading to altered electron transfer to redox partners. A single amino acid change can affect protein stability and cause a severe reduction in POR activity. Molecular characterisation of individual POR mutations is crucial for a better understanding of the impact on different redox partners of POR.

Synthesis and Structure–Activity Relationships of Novel Non-Steroidal CYP17A1 Inhibitors as Potential Prostate Cancer Agents

Twenty new compounds, targeting CYP17A1, were synthesized, based on our previous work on a benzimidazole scaffold, and their biological activity evaluated. Inhibition of CYP17A1 is an important modality in the treatment of prostate cancer, which remains the most abundant cancer type in men. The biological assessment included CYP17A1 hydroxylase and lyase inhibition, CYP3A4 and P450 oxidoreductase (POR) inhibition, as well as antiproliferative activity in PC3 prostate cancer cells. The most potent compounds were selected for further analyses including in silico modeling. This combined effort resulted in a compound (comp 2, IC₅₀ 1.2 µM, in CYP17A1) with a potency comparable to abiraterone and selectivity towards the other targets tested. In addition, the data provided an understanding of the structure–activity relationship of this novel non-steroidal compound class.

El laboratorio en el diagnóstico multidisciplinar del desarrollo sexual anómalo o diferente (DSD)

Objetivos

El desarrollo de las características sexuales femeninas o masculinas acontece durante la vida fetal, determinándose el sexo genético, el gonadal y el sexo genital interno y externo (femenino o masculino). Cualquier discordancia en las etapas de diferenciación ocasiona un desarrollo sexual anómalo o diferente (DSD) que se clasifica según la composición de los cromosomas sexuales del cariotipo.

Contenido

En este capítulo se abordan la fisiología de la determinación y el desarrollo de las características sexuales femeninas o masculinas durante la vida fetal, la clasificación general de los DSD y su estudio diagnóstico clínico, bioquímico y genético que debe ser multidisciplinar. Los estudios bioquímicos deben incluir, además de las determinaciones bioquímicas generales, análisis de hormonas esteroideas y peptídicas, en condiciones basales o en pruebas funcionales de estimulación. El estudio genético debe comenzar con la determinación del cariotipo al que seguirá un estudio molecular en los cariotipos 46,XX ó 46,XY, orientado a la caracterización de un gen candidato. Además, se expondrán de manera específica los marcadores bioquímicos y genéticos en los DSD 46,XX, que incluyen el desarrollo gonadal anómalo (disgenesias, ovotestes y testes), el exceso de andrógenos de origen fetal (el más frecuente), fetoplacentario o materno y las anomalías del desarrollo de los genitales internos.

Perspectivas

El diagnóstico de un DSD requiere la contribución de un equipo multidisciplinar coordinado por un clínico y que incluya los servicios de bioquímica y genética clínica y molecular, un servicio de radiología e imagen y un servicio de anatomía patológica.

The laboratory in the multidisciplinary diagnosis of differences or disorders of sex development (DSD): I) Physiology, classification, approach, and methodologyII) Biochemical and genetic markers in 46,XX DSD

Objectives

The development of female or male sex characteristics occurs during fetal life, when the genetic, gonadal, and internal and external genital sex is determined (female or male). Any discordance among sex determination and differentiation stages results in differences/disorders of sex development (DSD), which are classified based on the sex chromosomes found on the karyotype.

Content

This chapter addresses the physiological mechanisms that determine the development of female or male sex characteristics during fetal life, provides a general classification of DSD, and offers guidance for clinical, biochemical, and genetic diagnosis, which must be established by a multidisciplinary team. Biochemical studies should include general biochemistry, steroid and peptide hormone testing either at baseline or by stimulation testing. The genetic study should start with the determination of the karyotype, followed by a molecular study of the 46,XX or 46,XY karyotypes for the identification of candidate genes.

Summary

46,XX DSD include an abnormal gonadal development (dysgenesis, ovotestes, or testes), an androgen excess (the most frequent) of fetal, fetoplacental, or maternal origin and an abnormal development of the internal genitalia. Biochemical and genetic markers are specific for each group.

Outlook

Diagnosis of DSD requires the involvement of a multidisciplinary team coordinated by a clinician, including a service of biochemistry, clinical, and molecular genetic testing, radiology and imaging, and a service of pathological anatomy.

Non-classic cytochrome P450 oxidoreductase deficiency strongly linked with menstrual cycle disorders and female infertility as primary manifestations

STUDY QUESTION

Can cytochrome P450 oxidoreductase deficiency (PORD) be revealed in adult women with menstrual disorders and/or infertility?

SUMMARY ANSWER

PORD was biologically and genetically confirmed in five adult women with chronically elevated serum progesterone (P) who were referred for oligo-/amenorrhea and/or infertility.

WHAT IS KNOWN ALREADY

PORD is an autosomal recessive disease typically diagnosed in neonates and children with ambiguous genitalia and/or skeletal abnormalities. It is responsible for the decreased activity of several P450 enzymes, including CYP21A2, CYP17A1 and CYP19A1, that are involved in adrenal and/or gonadal steroidogenesis. Little is known about the optimal way to investigate and treat patients with adult-onset PORD.

STUDY DESIGN, SIZE, DURATION

In this series, we report five adult females who were evaluated in three tertiary endocrine reproductive departments between March 2015 and September 2018.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Five women aged 19-38 years were referred for unexplained oligo-/amenorrhea and/or infertility. Genetic testing excluded 21-hydroxylase deficiency (21OH-D), initially suspected due to the increased 17-hydroxyprogesterone (17-OHP) levels. Extensive phenotyping, steroid profiling by mass spectrometry, pelvic imaging and next-generation sequencing of 84 genes involved in gonadal and adrenal disorders were performed in all patients. IVF followed by frozen embryo transfer (ET) under glucocorticoid suppression therapy was performed for two patients.

MAIN RESULTS AND THE ROLE OF CHANCE

All patients had oligomenorrhea or amenorrhea. None had hyperandrogenism. Low-normal serum estradiol (E2) and testosterone levels contrasted with chronically increased serum P and 17-OHP levels, which further increased after adrenocorticotrophic hormone (ACTH) administration. Despite excessive P, 17OH-P and 21-deoxycortisol rise after ACTH stimulation suggesting non-classic 21OH-D, CYP21A2 sequencing did not support this hypothesis. Basal serum cortisol levels were low to normal, with inadequate response to ACTH in some women, suggesting partial adrenal insufficiency. All patients harbored rare biallelic POR mutations classified as pathogenic or likely pathogenic according to the American College of Medical Genetics and Genomics standards. Pelvic imaging revealed bilateral ovarian macrocysts in all women. IVF was performed for two women after retrieval of a normal oocyte number despite very low E2 levels during ovarian stimulation. Frozen ET under glucocorticoid suppression therapy led to successful pregnancies.

LIMITATIONS, REASONS FOR CAUTION

The number of patients described here is limited and these data need to be confirmed on a larger number of women with non-classic PORD.

WIDER IMPLICATIONS OF THE FINDINGS

The diagnosis of PORD must be considered in infertile women with chronically elevated P and 17OH-P levels and ovarian macrocysts. Differentiation of this entity from non-classic 21OH-D is important, as the multiple enzyme deficiency requires a specific management. Successful fertility induction is possible by IVF, providing that P levels be sufficiently suppressed by glucocorticoid therapy prior to implantation.

STUDY FUNDING/COMPETING INTEREST(S)

No specific funding was used for this study. There are no potential conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Disorders of Sex Development: Classification, Review, and Impact on Fertility

In this review, the elements included in both sex determination and sex differentiation are briefly analyzed, exposing the pathophysiological and clinical classification of disorders or anomalies of sex development. Anomalies in sex determination without sex ambiguity include gonadal dysgenesis, polysomies, male XX, and Klinefelter syndrome (dysgenesis and polysomies with a female phenotype; and sex reversal and Klinefelter with a male phenotype). Other infertility situations could also be included here as minor degrees of dysgenesis. Anomalies in sex determination with sex ambiguity should (usually) include testicular dysgenesis and ovotesticular disorders. Among the anomalies in sex differentiation, we include: (1) males with androgen deficiency (MAD) that correspond to those individuals whose karyotype and gonads are male (XY and testes), but the phenotype can be female due to different hormonal abnormalities. (2) females with androgen excess (FAE); these patients have ovaries and a 46,XX karyotype, but present varying degrees of external genital virilization as a result of an enzyme abnormality that affects adrenal steroid biosynthesis and leads to congenital adrenal hyperplasia; less frequently, this can be caused by iatrogenia or tumors. (3) Kallman syndrome. All of these anomalies are reviewed and analyzed herein, as well as related fertility problems.

Novel CYP19A1 Mutations Extend the Genotype-Phenotype Correlation and Reveal the Impact on Ovarian Function

Context

The steroidogenic enzyme aromatase (CYP19A1) is required for estrogen biosynthesis from androgen precursors in the ovary and extragonadal tissues. The role of aromatase, and thus estrogens, is best illustrated by genetic variations of the CYP19A1 gene leading to aromatase deficiency or excess.

Objective

The objective of this work is to characterize novel CYP19A1 variants.

Design setting and patients

Variants causing aromatase deficiency were suspected in four 46,XX children of African and Indian origin by careful clinical phenotyping. Sequencing of the CYP19A1 gene identified novel variants. Minigene experiments, aromatase activity assay, and computational, and histological analysis were used to characterize the variants.

Main outcome measure and results

CYP19A1 variants were found in all patients: a deletion in intron 9 leading to p.P423_H503del, a delins variant at p.P154, and point variants p.V161D, p.R264C, p.R375C. Except for R264C, all variants showed a loss of function. Protein structure and dynamics studies were in line with functional assays. The 2 female patients with delins variants manifested with ambiguous genitalia at birth. Histologic investigation revealed normal ovarian tissue on one side and a streak gonad on the other. Two female patients presented with abnormal pubertal development and polycystic ovaries.

Conclusion

In girls, aromatase deficiency usually manifests at birth, but diagnosis may also be made because of abnormal pubertal development or ovarian torsion due to (poly)cystic ovaries. The ovary harboring CYP19A1 variants may present as streak gonad or appears normal at birth, but is then at very high risk to produce cysts with aging and is therefore prone to ovarian torsion.