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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. [ABSTRACT FROM AUTHOR]

The article focuses on the study of Male assignment in 5a-reductase type 2 deficiency with female external genitalia. Topics discussed include Posterior reversible encephalopathy syndrome (PRES) can occur in diverse situations and is characterized by seizures, impairment of consciousness, headaches, visual abnormalities, nausea, and vomiting; and most cases are caused by systemic hypertension but there are other etiological conditions and entities, including immunosuppressant drug use.

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. • This study presented in vitro functional study of fifteen SRD5A2 variants and explored the genotype–phenotype association in our patients with 5α-RD2 deficiency. • Our study showed fifteen SRD5A2 variants caused complete loss of 5α-RD2 enzyme activity (<8 %) by in vitro functional study. • Patients with different clinical phenotypes can have the same genotypes and we found no obvious genotype–phenotype association in our series patients. [ABSTRACT FROM AUTHOR]

The SRD5A2 gene that encodes SRD5A2 enzyme is placed on chromosome 2p23. The gene includes 5 exons that are translated into a 254-amino acid protein. To evaluate SRD5A2 gene that encodes SRD5A2 enzyme is placed on chromosome 2p23 accompany with biotinidase deficiency in case with ambiguous external genitalia. We investigated a case with ambiguous external genitalia for cytogenetic and gene mutation analysis. Gene mutation analysis and cytogenetic analysis were performed according to a standard DNA sequencing method and the present international standard nomenclature (ISCN), respectively. A Novel p.Arg179Ser (c.537 G>T) heterozygotes mutation on exon 3 of SRD5A2 gene accompany with biotinidase deficiency was detected. The chromosomal analysis result is 46, XY. This is the first case with biotinidase deficiency and novel R179S p.Arg179Ser (c.537 G>T) mutation of the SRD5A2 gene, which cause 5-alpha reductase deficiency. [ABSTRACT FROM AUTHOR]

Background Testicular morphology and immunohistochemical studies have never been reported in genetically documented adult patients with 5 alpha-reductase type 2 deficiency (5α-R2 deficiency). Case presentation We describe the testicular histopathology of a 17-year-old XY subject with 5α-R2 deficiency caused by the recurrent homozygous Gly115Asp loss of function mutation of the SRD5A2 gene. We also performed an immunohistochemical analysis in order to further study the relationship between seminiferous tubules structure, Sertoli cell differentiation and androgenic signaling impairment in this case. We thus evaluated the testicular expression of theanti-Müllerian hormone (AMH), androgen receptor (AR) and 3β-hydroxysteroid dehydrogenase (3ßHSD). Histological analysis revealed a heterogeneous aspect with a majority (92%) of seminiferous tubules (ST) presenting a mature aspect but containing only Sertoli cells and devoid of germ cells and spermatogenesis. Focal areas of immature ST (8%) were also found. Testicular AR and 3βHSD expression were detected in adult male control, 5α-R2 deficiency and CAIS subjects. However, AMH expression was heterogeneous (detectable only in few AR negative prepubertal ST, but otherwise repressed) in the 5α-R2 deficiency, conversely to normal adult testis in which AMH was uniformly repressed and to an adult CAIS testis in which AMH was uniformly and strongly expressed. Conclusion Intratesticular testosterone can repress AMH by itself, independently of its metabolism into dihydrotestosterone. We also compare our results to the few post pubertal cases of 5α-R2 deficiency with available histological testicular description, reported in the literature. We will discuss these histological findings, in the more general context of evaluating the fertility potential of these patients if they were raised as males and were azoospermic. [ABSTRACT FROM AUTHOR]

Objective: To investigate the functional change of SRD5A2 gene mutations identified in patients with 5α-reductase type 2 deficiency. Patients and Methods: Three unrelated subjects born with ambiguous genitalia were included. All patients were initially reared as girls, but they gradually exhibited variable degrees of virilization at puberty without breast development, followed by a change of gender role. Sequencing analysis of the SRD5A2 gene was performed and enzymatic activities of 5α-reductase type 2 were assessed. Results: Three compound heterozygous mutations in the SRD5A2 gene were identified: patient 1 with p.G203S/ c.655delT, patient 2 with p.Q6X/p.G203S, and patient 3 with p.G203S/c.755_756insT. Heterozygosity for the p.V89L polymorphism was also found in patients 2 and 3. The c.655delT mutation led to a complete loss of the enzymatic activity, whereas mutants p.G203S and c.755_756insT resulted in a reduction of the enzymatic activities by 60 and 90%, respectively. Conclusion: Two frameshift heterozygous mutations, c.655delT and c.755_756insT, led to a dramatic reduction in 5α-reductase activity, and the latter had not been reported previously. In addition, the heterozygous mutation (p.G203) identified in the 3 patients presumably suggests a founder effect in the Chinese population and may explain the similarity in phenotype among the patients. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to perform a 5α-reductase type 2 gene (SRD5A2) analysis in 6 Korean patients with external genitalia ranging from predominantly female to male in whom 5α-reductase type 2 deficiency was suspected. Patients: Six patients from five unrelated families participated, and all of their parents were non-consanguineous. Three patients presented with ambiguous genitalia at birth, and 2 were referred owing to delayed puberty. The other patient was presented incidentally during an operation for inguinal hernia. Basal and post-human chorionic gonadotropin-stimulated serum testosterone and dihydrotestosterone levels were determined, but neither the levels nor ratio yielded enough information for differential diagnosis. Confirmative diagnosis was achieved by SRD5A2 gene analysis. Results: Four different pathologic mutations were identified. All have already been reported, and are located in exon 1 (p.Q6X), exon 4 (p.G203S and c.655delT), and exon 5 (p.R246Q). p.R246Q was the most frequently identified mutation in our study, and c.655delT has been detected only in Korean patients to date. Conclusion: The molecular analysis is the most reliable method for a correct diagnosis of 5α-reductase type 2 deficiency. Identification of mutations also enables genetic counseling for families at risk. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Objective: To describe two unrelated Thai patients with suspected 5α-reductase type 2 deficiency and perform mutation analysis of the SRD5A2 gene. Design: Case report. Setting: A pediatric endocrinology clinic at a university hospital. Patient(s): Two unrelated patients with 46,XY karyotype, born with ambiguous genitalia, were studied. One was reared as a boy and the other was reared as a girl. Intervention(s): The entire coding regions of the SRD5A2 gene were assessed by polymerase chain reaction (PCR) and sequencing analysis. Main Outcome Measure(s): Molecular characterization of the SRD5A2 gene. Result(s): Four different pathogenic mutations (three missense and one nonsense) were identified. These were located at exon 1 (p.Q6X and p.L20P), exon 3 (p.G183S), and exon 4 (p.G203S). The T>C transition (c.59T>C) resulting in a leucine-to-proline substitution at codon 20 (p.L20P) has not been previously described and was not detected in 100 unaffected, ethnic-matched control chromosomes. In addition, p.G183S, previously identified only among patients from mixed African–European ancestry and in the Dominican Republic, was also detected in a Thai patient. Conclusion(s): This study demonstrates that the SRD5A2 gene is responsible for 5α-reductase type 2 deficiency across different populations and emphasizes the important role of genetic testing for the definite diagnosis and genetic counseling before gender assignment or any surgical intervention. [Copyright &y& Elsevier]