European Journal of Pediatrics

, Volume 170, Issue 1, pp 1–8

Practical approach to steroid 5alpha-reductase type 2 deficiency

Review

DOI: 10.1007/s00431-010-1189-4

Cite this article as:
Cheon, C.K. Eur J Pediatr (2011) 170: 1. doi:10.1007/s00431-010-1189-4

Abstract

The aim of this article is to review the literature on steroid 5alpha-reductase type 2 deficiency (5α-RD2) to provide clinicians with information to guide their management of patients with this disorder. The 5alpha-reductase type 2 is encoded by the 5alpha-reductase type 2 gene (SRD5A2) on chromosome 2 and is predominantly expressed in external genital tissues and the prostate. Mutations of the SRD5A2 gene leads to an uncommon autosomal recessive disorder affecting sexual differentiation in individuals with 46,XY karyotype; their phenotype can range from almost normal female structures to a distinct male phenotype with ambiguous genitalia at birth. These phenotypes result from impaired conversion of testosterone to dihydrotestosterone due to mutations in the SRD5A2 gene. Patients exhibit virilization at puberty without breast development, which is often accompanied by gender identity change from female to male. More than 40 mutations have been reported in all five exons of the SRD5A2 gene. Phenotype–genotype correlations for 5α-RD2 have not been well established. The newborn phenotypes of male pseudohermaphrodites with 5α-RD2, partial androgen insensitivity syndrome (PAIS), or 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) enzyme deficiency may be indistinguishable. We conclude that steroid 5α-RD2 should be included in the differential diagnosis of newborns with 46,XY DSD. It is important that the diagnosis be made in infancy by biochemical and molecular studies before gender assignment or any surgical intervention because these patients should be considered males at birth.

Keywords

5alpha-reductase type 2 deficiency Ambiguous genitalia Gender identity SRD5A2 

Abbreviations

ACTH

adrenocorticotropic hormone

AIS

androgen insensitivity syndrome

PAIS

partial androgen insensitivity syndrome

AR

androgen receptor

DHT

dihydrotestosterone

DSD

disorders of sex development

AT

androstenedione

T

testosterone

17β-HSD3

17β-hydroxysteroid dehydrogenase type 3

SRD5A2

steroid 5alpha-reductase type 2 gene

5α-RD2

5alpha-reductase type 2 deficiency

hCG

human chorionic gonadotropin

SRY

sex-determining region of the Y chromosome

AMH

anti-Müllerian hormone

FSH

follicle-stimulating hormone

LH

luteinizing hormone

MRI

magnetic resonance imaging

WT-1

Wilms’ tumor-1

SF-1

steroidogenic factor 1

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Department of Pediatrics, Genetic and Endocrinologic Clinic, Children’s HospitalPusan National UniversityYangsan-siKorea

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