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) |
| Others |
| Urogenital malformations |
| Dysmorphic syndromes |
| Exogenous maternal oestrogens |