Table 17: Classification of intersex states (modified from Allen 1976). Major categories grouped by gonadal histology, subclassification by aetiology

I. Ovary only = female pseudohermaphrodite -*■ karyotype 46XX

A. Secondary to endogenous androgens (САН)

21-hydroxylase deficiency 11 (3-hydroxylase deficiency зр-ol-dehydrogenase deficiency

B. Secondary to maternal androgens (exogenous ingestion - endogenous production)

II. Testis only = male pseudohermaphrodite -> karyotype 46XY

A. Secondary to inadequate androgen (TST) production

20a-hydroxylase deficiency Зр-ol-dehydrogenase deficiency 17a-hydroxylase deficiency 17,20-desmolase deficiency 17-ketosteroid reductase deficiency

B. Secondary to inadequate conversion of TST to DHTST ► 5a reductase deficiency

С Secondary to inadequate androgen (TST/DHTST) utilization (androgen receptor deficiency)

Incomplete

Complete (testicular feminization) D. Secondary to deficient АМН -> hernia uteri inguinalis

III. Testis plus ovary = true hermaphrodite -> Karyotype 46XY, 46XX, mosaic

IV. Testis plus streak = mixed gonadal dysgenesis > karyotype most often 45XO/46XY

V. Streak plus streak = pure gonadal dysgenesis -> karyotype 45X0 (Turner's syndrome), 46XX, 46XY

VI. Miscellaneous (? Dysgenetic testes? teratogenic factors)

САН = congenital adrenal hyperplasia; TST = testosterone; АМН = anti-Mullerian hormone; DHTST = dihydrotestosterone.

10.2.1 Ovary only (female pseudohermaphrodite)

46XX patients with normal ovaries and uterus, with virilized external genitalia due to the endogenous overproduction of androgens by the foetal adrenal glands (САН, AGS). These patients account for approximately two-thirds of intersex states in clinical practice.

Testis only (male pseudohermaphrodite)

46XY patients with inadequate virilization of the external genitalia due to deficient biosynthesis of TST, inadequate conversion of TST to DHTST (lack of 5a-reductase) or inadequate TST/DHTST utilization (lack of androgen receptors). Also patients with АМН deficiency with adequate male external genitalia and retained Mullerian structures, i.e. tubes and uterus (hernia uteri inguinalis).

Testis plus ovary (true hermaphrodite)

Patients possess both ovarian and testicular tissue in various combinations. Their karyotype varies, i.e. 46XX, 46XY or mosaic 46XX/46XY. True hermaphrodites make up approximately 10% of intersex cases.

Testis plus streak gonad (mixed gonadal dysgenesis)

The second most common category of intersexuality. Most common karyotype 45XO/46XY mosaicism. The existing testis is infertile and Mullerian structures may be present on both sides. There is a high risk of gonadoblastoma of the existing testis after puberty.