Prenatal diagnosis and successful intrauterine treatment of a female fetus with 21-hydroxylase deficiency.

OBJECTIVE

To present the first reported Australian case of prenatal treatment of a female fetus with congenital adrenal hyperplasia resulting from 21-hydroxylase deficiency.

CLINICAL FEATURES

A couple whose son had congenital adrenal hyperplasia resulting from 21-hydroxylase deficiency sought prenatal diagnosis and treatment in their next pregnancy.

INTERVENTION

Maternal treatment with dexamethasone was commenced at seven weeks' gestation to suppress androgen production by the fetal adrenal glands and prevent virilisation of an affected female fetus. At ten weeks' gestation chorionic villus sampling demonstrated a female fetus, who was shown subsequently to be affected by means of a linkage method in which probes to HLA genes DQA and DRB were used as markers for the 21-hydroxylase genes. Increased 17-hydroxyprogesterone and androstenedione immunoactivity in amniotic fluid obtained at 14.5 weeks confirmed the fetus to be affected and demonstrated incomplete suppression of fetal adrenal androgen production. Dexamethasone was continued to term and maintained suppression of the fetal and maternal adrenal glands.

OUTCOME

The infant was born with normal female genitalia. Growth retardation was present but the relationship between this and the dexamethasone treatment remains uncertain. The mother had excessive weight gain during pregnancy.

CONCLUSION

Dexamethasone treatment commenced in the first weeks of pregnancy can prevent or reduce virilisation of female fetuses with congenital adrenal hyperplasia resulting from 21-hydroxylase deficiency.