3ß-Dehydrogenase deficiency is a very rare cause of CAH in which synthesis of all steroid hormones is impaired. There is excessive production of the precursors: Pregnenolone, 17-Hydroxypregnenolone and DehydroepiAndrosterone Sulphate (DHEAS).
The classical presentation is in early infancy with adrenal insufficiency (see section on adrenal insufficiency). Females may also present with a mild degree of virilisation due to the excess production of DHEAS (a small fraction of which can be converted to testosterone in the periphery). The external genitalia of the male patient may range from minor developmental problems to actual external female genitalia. This depends on the residual testosterone activity.
The aim of the treatment is to replace any deficient hormones. Plastic surgery in some cases may also be required.