Definition

Biallelic pathogenic variants in the SRD5A2 gene disable the 5α-reductase type 2 enzyme, which carries out the peripheral conversion of testosterone to dihydrotestosterone (DHT). DHT deficiency disrupts male-typical differentiation of the external genitalia during the embryonic period; individuals with a 46,XY genotype show undervirilization ranging from ambiguous genitalia to a nearly typical female appearance. At puberty, the rise in testosterone can bring on marked virilization (deepening of the voice, increased muscle mass).

Gene/region examined

SRD5A2 - Exon 1, SRD5A2 - Exon 2, SRD5A2 - Exon 3, SRD5A2 - Exon 4, SRD5A2 - Exon 5

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Hereditary, autosomal recessive (AR).

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

Go to term →

Carrier (Heterozygous / Homozygous)

Why it matters: In autosomal recessive inheritance, when each parent is a carrier (while both appear healthy), the chance of their child being born with the disease is 25% in each

Go to term →

VUS (Variant of Uncertain Significance)

This is the situation where the test has detected a change in the DNA, but the role of this change in the development of disease is unconfirmed.

Go to term →

How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

Go to term →

Types of Genetic Tests

A genetic test is a type of medical test that detects changes in genes, chromosomes or proteins. Today there are more than 77,000 genetic tests available.

Go to term →