Endocrinology: Disorders Of Sex Development

Question 1

What gene is responsible for the differentiation of the gonad into a testis?

Answer 1

The testis determining gene on the Y chromosome = SRY gene

Question 2

What happens in the absence of the SRY gene?

Answer 2

The gonad becomes ovaries and the genitalia female

Question 3

A disorder of sex development may be due to excessive androgens producing virilisation in a female. The most common cause is…

Answer 3

Congenital adrenal hyperplasia

Question 4

A DSD may be due to inadequate androgen action producing under virilisation in males. This can result from…

Answer 4

Inability to respond to androgens ie a receptor problem - androgen insensitivity syndrome (may be complete or partial)
Or inability to convert testosterone to dihydrotestosterone (5 alpha reductase deficiency)
Or abnormalities in synthesis of androgens from cholesterol

Question 5

A DSD may be due to gonadotropin insufficiency, which is seen in several syndromes such as..

Answer 5

Prader-Willi syndrome

Congenital pituitary dysfunction

Question 6

Before the most appropriate sex of reading is decided upon, what should be determined?

Answer 6

The karyotype
Adrenal and sex hormone levels measured
US of internal structures and gonads
Sometimes laparoscopic imaging and biopsy of internals structures required