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PAEDIATRIC UROLOGY

10.2 Classification

The classification proposed by Allen in 1976 (based on gonadal histology with subclassifications made primarily by aetiology), has the advantage that gonadal histology is less uncertain to interpret than is dependence on karyotype or morphology of the external genitalia.

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

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

  2. 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