Genotype-phenotype correlation, gonadal malignancy risk, gender preference, and testosterone/dihydrotestosterone ratio in steroid 5-alpha-reductase type 2 deficiency: a multicenter study from Turkey

In vitro functional study of fifteen SRD5A2 variants found in Chinese patients and the relation between the SRD5A2 genotypes and phenotypes

The 5α-reductase type 2 (5α-RD2) deficiency is one of the most common etiology of 46, XY disorders of sex development and is caused by pathogenic variants in SRD5A2. Massively parallel sequencing contributes to identification of numerous novel SRD5A2 variants, in vitro functional study could help to determine their pathogenicity. In this study, we aim to present the functional study of fifteen SRD5A2 variants found in Chinese patients and explore the genotype-phenotype association. We collected the clinical manifestation and genotype of 38 patients with 5α-RD2 deficiency who visited our center between 2009 and 2021. The pathogenicity of seven missense SRD5A2 variants, were predicted by in-silico tools. Furthermore, fifteen SRD5A2 variants without reported functional assay were studied in vitro to analyze the role of these variants in enzymatic activity. Twenty-four SRD5A2 rare variants were identified in 38 patients with 5α-RD2 deficiency. Fifteen variants without reported functional assay decreased the conversation of testosterone (T) to dihydrotestosterone(DHT) and caused the almost complete loss of enzyme activity (<8 %) in our in-vitro functional study. Thirty-eight patients with three different external genital phenotypes (complete female, clitoromegaly and hypospadias) were found to have same variants. Patients with different testicular position (scrotum/clitoris and cryptorchidism) were found to have same variants. Our study showed 15 SRD5A2 variants caused complete loss of 5α-RD2 enzyme activity by functional study. Patients with different clinical phenotypes can have the same genotypes and no obvious genotype-phenotype association exist in our series patients.

Genotype-phenotype correlations, surgical selections, and postoperative complications of 5α-reductase 2 deficiency in 69 children with hypospadias

5α-reductase 2 deficiency prevents testosterone from being converted to dihydrotestosterone, which causes abnormal urogenital sinus development. The aim of this study was to analyze the relationship between genotype-phenotype, surgical selections, and postoperative complications of 5α-reductase 2-deficient patients with hypospadias. We retrospectively evaluated the medical records of patients who were diagnosed with 5α-reductase 2 deficiency after genetic testing in the Department of Endocrinology and underwent initial hypospadias surgery in the Department of Urology in Beijing Children's Hospital, Capital Medical University (Beijing, China), from April 2007 to December 2021. A total of 69 patients were included in this study; the mean age at surgery was 34.1 months, and the average follow-up time was 54.1 months. Sixty children were treated with preoperative hormone stimulation (PHS) to promote penile growth. The average penis length and glans width were increased by 1.46 cm and 0.62 cm, respectively. The most frequent mutations were p.R227Q (39.1%, 54/138), p.Q6* (15.2%, 21/138), p.G203S (12.3%, 17/138), and p.R246Q (11.6%, 16/138). In 64 patients who were followed up, 43 had a one-stage operation and 21 had a staged operation, and there were significant differences in external masculinization score (EMS) ( P = 0.008) and the average number of operation required to cure ( P < 0.001) between one-stage and staged operations. PHS had a positive effect ( P < 0.001) on penile development. The p.R227Q mutation was associated with higher EMS and less severe hypospadias. One-stage surgery can be selected if conditions permit. The growth and development of children are acceptable in the long term, but penis growth remains unsatisfactory. Long-term complications of hypospadias should be considered during puberty.

The Genotype-Phenotype Correlation in Human 5α-Reductase Type 2 Deficiency: Classified and Analyzed from a SRD5A2 Structural Perspective

The phenotype of the 5α-reductase type 2 deficiency (5αRD2) by the SRD5A2 gene mutation varies, and although there have been many attempts, the genotype-phenotype correlation still has not yet been adequately evaluated. Recently, the crystal structure of the 5α-reductase type 2 isozyme (SRD5A2) has been determined. Therefore, the present study retrospectively evaluated the genotype-phenotype correlation from a structural perspective in 19 Korean patients with 5αRD2. Additionally, variants were classified according to structural categories, and phenotypic severity was compared with previously published data. The p.R227Q variant, which belongs to the NADPH-binding residue mutation category, exhibited a more masculine phenotype (higher external masculinization score) than other variants. Furthermore, compound heterozygous mutations with p.R227Q mitigated phenotypic severity. Similarly, other mutations in this category showed mild to moderate phenotypes. Conversely, the variants categorized as structure-destabilizing and small to bulky residue mutations showed moderate to severe phenotypes, and those categorized as catalytic site and helix-breaking mutations exhibited severe phenotypes. Therefore, the SRD5A2 structural approach suggested that a genotype-phenotype correlation does exist in 5αRD2. Furthermore, the categorization of SRD5A2 gene variants according to the SRD5A2 structure facilitates the prediction of the severity of 5αRD2 and the management and genetic counseling of patients affected by it.

Consensus guide on prophylactic gonadectomy in different sex development

The risk of suffering from gonadal germ cell tumors (GCT) is increased in some patients with different sexual development (DSD), mainly in those with Y chromosome material. This risk, however, varies considerably depending on a multitude of factors that make the decision for prophylactic gonadectomy extremely difficult. In order to make informed recommendations on the convenience of this procedure in cases where there is potential for malignancy, this consensus guide evaluates the latest clinical evidence, which is generally low, and updates the existing knowledge in this field.

Genotype-Phenotype Correlation Analysis and Identification of a Novel SRD5A2 Mutation in Four Unrelated Chinese Patients with 5α-Reductase Deficiency

Objective

The 5α-reductase type 2 deficiency is mainly caused by mutations in the SRD5A2 gene. Our study aims to investigate the SRD5A2 gene mutations and their corresponding manifestations.

Methods

Four unrelated Chinese patients with 46, XY ambiguous genitalia were studied. Molecular genetic alterations and clinical presentations were analyzed.

Results

Five variants in the SRD5A2 gene were identified, all highly conserved in vertebrate orthologs. The p.P251A was a novel variant, predicted to “Affect protein function” and to be “probably damaging”. Combining patients’ gene mutations with their external genitalia and male sexual characteristics, we found that three variants, p.Q6X, p.N193S, and p.H90Y, were associated with severe undervirilization of external genitalia, and the other two, p.G203S and p.P251A, probably retained part of the enzyme activity.

Conclusion

Mutation analysis of SRD5A2 gene is crucial for differential diagnosis in patients with 5α-reductase type 2 deficiency. Patients’ variable manifestations depend on the mutation type and residual enzyme activity. The novel variant p.P251A enlarges the spectrum of SRD5A2 mutations.

The Molecular Basis of 5α-Reductase Type 2 Deficiency

The 5α-reductase type 2 enzyme catalyzes the conversion of testosterone into dihydrotestosterone, playing a crucial role in male development. This enzyme is encoded by the SRD5A2 gene, which maps to chromosome 2 (2p23), consists of 5 exons and 4 introns, and encodes a 254 amino acid protein. Disruptions in this gene are the molecular etiology of a subgroup of differences of sex development (DSD) in 46,XY patients. Affected individuals present a large range of external genitalia undervirilization, ranging from almost typically female external genitalia to predominantly typically male external genitalia with minimal undervirilization, including isolated micropenis. This is an updated review of the implication of the SRD5A2 gene in 5α-reductase type 2 enzyme deficiency. For that, we identified 451 cases from 48 countries of this particular 46,XY DSD from the literature with reported variants in the SRD5A2 gene. Herein, we present the SRD5A2 mutational profile, the SRD5A2 polymorphisms, and the functional studies related to SRD5A2 variants to detail the molecular etiology of this condition.

Clinical, Hormonal, and Genetic Characteristics of 5α-Reductase Type 2 Deficiency in 103 Chinese Patients

OBJECTIVE

5α-Reductase type 2 (5α-RD2) deficiency causes variable degrees of undervirilization in patients. The correlation between its genotype and phenotype is unclear.

METHODS

We retrospectively evaluated 103 patients with 46,XY disorders of sex development who were diagnosed with 5α-RD2 deficiency.

RESULTS

The prevalence of female sex assignment (P = .008) and the incidences of cryptorchidism (P = .0003) and bifid scrotum (P = .0002) in the non-p.R227Q variant group were higher, but there were no significant differences in the incidences of hypospadias and isolated microphallus. The external masculinization score in the non-p.R227Q variant group was lower than that in the homozygous p.R227Q variant (P = .019) and compound heterozygous p.R227Q variant groups (P = .013). The level of anti-Mullerian hormone in the non-p.R227Q variant group was lower than that in the homozygous p.R227Q variant (P < .001) and compound heterozygous p.R227Q variant groups (P = .006). The testosterone-to-dihydrotestosterone ratio of the homozygous p.R227Q variant group was higher than that of the non-p.R227Q variant (P = .018) and compound heterozygous p.R227Q variant groups (P = .029). Twenty-three reportedly pathogenic variants and 11 novel steroid 5α-reductase 2 (SRD5A2) variants were identified.

CONCLUSION

Compared with patients without p.R227Q, patients with p.R227Q exhibited higher external masculinization scores and anti-Mullerian hormone expression, a lower prevalence of female sex assignment, and lower incidences of cryptorchidism and bifid scrotum. We identified 23 reportedly pathogenic SRD5A2 variants and 11 novel SRD5A2 variants that led to 5α-RD2 deficiency. We established a genotype-phenotype correlation, and patients with p.R227Q showed a relatively mild phenotype.

The Impact of the CEDD-NET on the Evaluation of Rare Disorders: A Multicenter Scientific Research Platform in the Field of Pediatric Endocrinology

OBJECTIVE

The database http://cedd.saglik-network.org (CEDD-NET) has been operating since 2013 in Turkey. All pediatric endocrinologists can propose projects to this network. The aim of our study was to determine the impact of CEDD-NET on the transformation of multicenter studies into scientific publications and assess the academic characteristics of the studies that have been transcribed into publication.

METHODS

All the studies that were opened to patient admission on the website between August 26, 2013 and March 1, 2021 were reviewed.

RESULTS

A total of 30 studies were accepted and opened for data entry. The median data collection period was 12 (1.5-24) months, while the median number of researchers participated was 23 (3-180), the median number of cases was 120 (26-192). The average cost was $2113 (1370-3118). Out of 30 studies, data entry was completed for 27. Sixteen publications were produced from 14 studies, 13 ot them have not published yet. The median time from the end of data entry to publication of the study was 686 (168-1608) days. While the median impact factor of the journals in which the studies were published was 1.803 (1.278-5.399), the median number of citations was 6.5 (0-49), and cited by 99 times in Web of Science indexed journals in total.

CONCLUSION

CEDD-NET appears to be productive and effective as all the publications are of high quality that have been published in the Q1-Q2 categories. This study demonstrated the benefits and necessity of establishing nationwide databases, even covering more than one country, in specialized branches, such as pediatric endocrinology where rare diseases are of concern.

Differences of adrenal-derived androgens in 5α-reductase deficiency versus androgen insensitivity syndrome

Steroid 5α‐reductase type 2 deficiency (5α‐RD2) and androgen insensitivity syndrome (AIS) are difficult to distinguish clinically and biochemically, and adrenal‐derived androgens have not been investigated in these conditions using modern methods. The objective of the study was to compare Chinese patients with 5α‐RD2, AIS, and healthy men. Sixteen patients with 5α‐RD2, 10 patients with AIS, and 39 healthy men were included. Serum androgen profiles were compared in these subjects using liquid chromatography/tandem mass spectrometry (LC‐MS/MS). Based on clinical features and laboratory tests, 5α‐RD2 and AIS were diagnosed and confirmed by genotyping. Dihydrotestosterone (DHT) and testosterone (T) were both significantly lower in patients with 5α‐RD2 than AIS (p < 0.0001). The T/DHT ratio was higher in 5α‐RD2 (4.5–88.6) than AIS (13.4–26.7) or healthy men (7.6–40.5). Using LC‐MS/MS, a cutoff T/DHT value of 27.3 correctly diagnosed 5α‐RD2 versus AIS with sensitivity 93.8% and specificity 100%. Among the adrenal‐derived 11‐oxygenated androgens, 11β‐hydroxyandrostenedione (11OHA4) and 11‐ketoandrostenedione (11KA4) were also lower in patients with 5α‐RD2 than those of patients with AIS. In contrast, 11β‐hydroxytestosterone (11OHT) was higher in 5α‐RD2 than AIS. Furthermore, a 11OHT/11OHA4 cutoff value of 0.048 could also distinguish 5α‐RD2 from AIS. Thus, both elevated T/DHT values above 27.3 and the unexpected 11‐oxygenated androgen profile, with a 11OHT/11OHA4 ratio greater than 0.048, distinguished 5α‐RD2 from AIS. These data suggest that the metabolism of both gonadal and adrenal‐derived androgens is altered in 5α‐RD2.

Anti-androgenic, anti-oxidant and anti-apoptotic effects of the aqueous and methanol extracts of Pterorhachis zenkeri (Meliaceae): Evidence from in vivo and in vitro studies

The aim of this study was to evaluate the effects of Pterorhachis zenkeri (Meliaceae) on sex organ growth in immature male rats and, oxidative stress and apoptosis markers in CCL-97 (R2C) Leydig cells. For the in vivo studies, 70 immature male Wistar rats (n = 10/group) were treated for 2 or 4 weeks with: distilled water (10 ml/kg, per os) plus soya oil (1 ml/kg, sc), bicalutamide (10 mg/kg, per os), aqueous or methanol extract of P. zenkeri (10 mg/kg or 62 mg/kg, per os) or testosterone propionate (3 mg/kg, sc). After each treatment period, body and sexual organ weights, plasmatic testosterone, total proteins and total cholesterol levels were measured. In the in vitro test, the effects of the methanol extract of P. zenkeri on cell viability, apoptosis, reactive oxygen species (ROS) production, intracellular calcium release and caspases 3/9 were assessed using CCL-97 Leydig cells. Pterorhachis zenkeri extracts decreased sex organ weights, plasmatic testosterone and protein levels in rats. In the in vitro studies, P. zenkeri inhibited apoptosis, ROS production, calcium release and caspase 3/9 activities. These results suggest that P. zenkeri has anti-androgenic, anti-oxidant and anti-apoptotic activities with methanol extract being the most active and could be an effective alternative for the management of androgen-related diseases.

Clinical characteristics and genotype-phenotype correlations of 130 Chinese children in a high-homogeneity single-center cohort with 5α-reductase 2 deficiency

Background

Patients with steroid 5α‐reductase 2 deficiency (5α‐RD) caused by SRD5A2 (OMIM #607306) variants present variable genotypes and phenotypes. The genotype‐phenotype correlations remain unclear.

Methods

We investigated genotype‐phenotype correlations of SRD5A2 variants in a large Chinese single‐center cohort. Phenotypes were categorized using the external masculinization score (EMS), urethral meatus and gonad position, and penile length‐standard deviation score.

Results

Of the 130 included patients, 113 had hypospadias, and 17 had a normal urethral meatus position. Testosterone/dihydrotestosterone (T/DHT) values were not significantly associated with phenotypic severity (p = 0.539–0.989). Of the 31 SRD5A2 variants, including 10 novel variants, p.R227Q was the most prevalent (39.62%), followed by p.Q6* (16.92%), p.R246Q (13.46%), and p.G203S (10.38%). Compared to biallelic missense mutations, biallelic nonsense mutations were associated with a lower EMS and urethral meatus score (p = 0.009 and p = 0.024, respectively). Patients homozygous for p.R227Q exhibited mild and variable phenotypes, while those homozygous for p.Q6*, p.R246Q, or p.G203S showed consistently severe phenotypes. The phenotypes were variable and milder in patients with compound heterozygosity for p.R227Q and these mutations.

Conclusion

T/DHT does not predict phenotype severity. The most prevalent SRD5A2 variant in Han Chinese is p.R227Q, which is associated with milder phenotypes and greater phenotypic variability. SRD5A2 variants may significantly influence phenotypic variation.

Under-reported aspects of diagnosis and treatment addressed in the Dutch-Flemish guideline for comprehensive diagnostics in disorders/differences of sex development

We present key points from the updated Dutch-Flemish guideline on comprehensive diagnostics in disorders/differences of sex development (DSD) that have not been widely addressed in the current (inter)national literature. These points are of interest to physicians working in DSD (expert) centres and to professionals who come across persons with a DSD but have no (or limited) experience in this area. The Dutch-Flemish guideline is based on internationally accepted principles. Recent initiatives striving for uniform high-quality care across Europe, and beyond, such as the completed COST action 1303 and the European Reference Network for rare endocrine conditions (EndoERN), have generated several excellent papers covering nearly all aspects of DSD. The Dutch-Flemish guideline follows these international consensus papers and covers a number of other topics relevant to daily practice. For instance, although next-generation sequencing (NGS)-based molecular diagnostics are becoming the gold standard for genetic evaluation, it can be difficult to prove variant causality or relate the genotype to the clinical presentation. Network formation and centralisation are essential to promote functional studies that assess the effects of genetic variants and to the correct histological assessment of gonadal material from DSD patients, as well as allowing for maximisation of expertise and possible cost reductions. The Dutch-Flemish guidelines uniquely address three aspects of DSD. First, we propose an algorithm for counselling and diagnostic evaluation when a DSD is suspected prenatally, a clinical situation that is becoming more common. Referral to ultrasound sonographers and obstetricians who are part of a DSD team is increasingly important here. Second, we pay special attention to healthcare professionals not working within a DSD centre as they are often the first to diagnose or suspect a DSD, but are not regularly exposed to DSDs and may have limited experience. Their thoughtful communication to patients, carers and colleagues, and the accessibility of protocols for first-line management and efficient referral are essential. Careful communication in the prenatal to neonatal period and the adolescent to adult transition are equally important and relatively under-reported in the literature. Third, we discuss the timing of (NGS-based) molecular diagnostics in the initial workup of new patients and in people with a diagnosis made solely on clinical grounds or those who had earlier genetic testing that is not compatible with current state-of-the-art diagnostics.

Integrative and Analytical Review of the 5-Alpha-Reductase Type 2 Deficiency Worldwide

Introduction

The conversion of testosterone into dihydrotestosterone is catalyzed by the 5α-reductase type 2 enzyme which plays a crucial role in the external genitalia virilization. It is encoded by the SRD5A2 gene. Allelic variants in this gene cause a 46,XY DSD with no genotype-phenotype relationship. It was firstly reported in the early 70s from isolated clusters. Since then, several cases have been reported. Putting together, it will expand the knowledge on the molecular bases of androgen milieu.

Methods

We searched for SRD5A2 allelic variants (AV) in the literature (PubMed, Embase, MEDLINE) and websites (ensembl, HGMD, ClinVar). Only cases with AV in both alleles, either in homozygous or compound heterozygous were included. The included cases were analyzed according to ethnicity, exon, domain, aminoacid (aa) conservation, age at diagnosis, sex assignment, gender reassignment, external genitalia virilization and functional studies. External genitalia virilization was scored using Sinnecker scale. Conservation analysis was carried out using the CONSURF platform. For categorical variables, we used X2 test and Cramer's V. Continuous variables were analyzed by t test or ANOVA. Concordance was estimated by Kappa.

Results

We identified 434 cases of 5ARD2 deficiencies from 44 countries. Most came from Turkey (23%), China (17%), Italy (9%), and Brazil (7%). Sixty-nine percent were assigned as female. There were 70% of homozygous allelic variants and 30% compound heterozygous. Most were missense variants (76%). However, small indels (11%), splicing (5%) and large deletions (4%) were all reported. They were distributed along with all exons with exon 1 (33%) and exon 4 (25%) predominance. Allelic variants in the exon 4 (NADPH-binding domain) resulted in lower virilization (p<0.0001). The codons 55, 65, 196, 235 and 246 are hotspots making up 25% of all allelic variants. Most of them (76%) were located at conserved aa. However, allelic variants at non-conserved aa were more frequently indels (28% vs 6%; p<0.01). The overall rate of gender change from female to male ranged from 16% to 70%. The lowest rate of gender change from female to male occurred in Turkey and the highest in Brazil. External genitalia virilization was similar between those who changed and those who kept their assigned gender. The gender change rate was significantly different across the countries (V=0.44; p<0.001) even with similar virilization scores.

Conclusion

5ARD2 deficiency has a worldwide distribution. Allelic variants at the NADPH-ligand region cause lower virilization. Genitalia virilization influenced sex assignment but not gender change which was influenced by cultural aspects across the countries. Molecular diagnosis influenced on sex assignment, favoring male sex assignment in newborns with 5α-reductase type 2 deficiency.