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Typical and atypical sex development


  How an embryo develops as male or female

> Sex chromosomes

> Sex determination and formation of the gonads

> Development of external genitals

> Development of internal sex organs

Formation of the sexual ducts

Testicular descent

> Development of other sex-specific features

> Sex-specific brain development

> The HPG axis and its role in sex development

> Sex, gender and sexual orientation

  Atypical sexual development & DSD

A word on nomenclature

Classifying variation in sex development

Information provided on this website

  Variations obvious at birth

> Undescended testes

> Unusually small penis

> Unusually large clitoris

> Ambiguous genitals

> Hypospadias

> Enlarged breasts

  Variations appearing later in childhood

Atypical gender behaviour

  Variations appearing at puberty

  Variations appearing in adulthood

Infertility associated with DSD

  Other sources of information


For clinicians and scientists [COMING SOON]

  Types of DSD and their causes

> Sex chromosome DSD

A: 47,XXY DSD (Klinefelter syndrome)

B: 45,X DSD (Turner syndrome)

C: 45,X/46,XY DSD (X0/XY mosaicism)

D: 46,XX/46,XY DSD (XX-XY chimerism)

> 46,XY DSD

A: Primary disorders of testicular development

1. Complete or partial gonadal dysgenesis and 46,XY ovotesticular DSD

2. Testicular regression

B: Disorders of androgen synthesis

C: Disorders of androgen action

1. Androgen Insensitivity Syndrome

2. Drugs and environmental modulators of androgen action

D: Other disorders involving XY feminization

1. HPG axis defects

a. Congenital hypogonadotropic hypogonadism

b. LH receptor mutations

2. Persistent Müllerian duct syndrome

3. Isolated cryptorchidism

4. Isolated hypospadias

5. Other syndromic disorders and unknown gene defects

6. Environmental influences

> 46,XX DSD

A: Disorders of ovarian development

B: Disorders involving androgen excess

1. Fetal, including CAH

2. Fetoplacental

3. Maternal

C: Other disorders involving XX masculinization

1. Müllerian agenesis/hypoplasia

2. Uterine abnormalities

3. Vaginal atresia

4. Labial adhesions

5. Other syndromic disorders

6. Environmental influences

  DSD Gene mutation databases

  Diagnosis of DSD

  Collecting samples and patient data for research

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  The NHMRC Program in Human DSD

  Chief investigators

  Contributors to this website

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Last updated: 9 October 2013