Table 2

Disorders of sex differentiation

Virilisation of XX females
Increased fetal adrenal androgen production
    Congenital adrenal hyperplasia (3β-hydroxysteroid dehydrogenase deficiency, 21-hydroxylase deficiency, 11β-hydroxylase deficiency)
    Androgen secreting tumour
    Placental aromatase deficiency
Fetal gonadal androgen production
    True hermaphrodite with both testicular and ovarian tissue
Transplacental passage of maternal androgens
    Drugs administered during pregnancy: e.g. progesterone, danazol
    Maternal androgen secreting tumour, luteoma of pregnancy
Other causes
    Dysmorphic syndromes
    Prematurity—prominent clitoris
Bisexual gonads
    Hermaphroditism. Usual genotype 46XX
Undervirilisation of XY males
Testicular dysgenesis/malfunction
    Pure XY gonadal dysgenesis
    Mixed gonadal dysgenesis–45X/46XY. May be associated with gene mutations on SRY, SOX9, or WT1 genes
    Dysgenetic testis
    Testicular regression syndromes
        True agonadism, rudimentary testis syndrome
Biosynthetic defect—decreased fetal androgen biosynthesis
    Leydig cell hypoplasia (LH deficiency or LH receptor defect)
    Testosterone biosynthesis (non-virilising CAH): (StAR, 3β-HSD, 17α-OHD/17–20 lyase, Smith-Lemli-Opitz syndrome)
    5α-reductase deficiency
    Deficient synthesis or action of AMH—persistent Müllerian duct syndrome. May be due to mutations in AMH or AMH receptor gene or SF1 gene
End organ unresponsiveness
    Androgen receptor and post-receptor defects (complete and incomplete androgen insensitivity syndrome)
    Urogenital malformations
    Dysmorphic syndromes
    Exogenous maternal oestrogens