Prenatal diagnosis and treatment of steroid 21-hydroxylase deficiency (congenital adrenal hyperplasia).

Steroid 21-hydroxylase deficiency congenital adrenal hyperplasia is the most common cause of genital ambiguity in females at birth. Inhibited formation of cortisol causes increase in the release of ACTH in turn leading to overproduction of adrenal androgens. This predisposes the affected female fetus to prenatal development of genital ambiguity. A large number of patients also have aldosterone insufficiency which manifests after birth in form of inability to conserve sodium and to excrete potassium which can lead to adrenal shock and neonatal death, if left untreated. Prenatal diagnosis is possible using several methods like steroid assay of amniotic fluid and, HLA typing. Recently with advancement more accurate direct molecular genetic techniques have been utilized on chorionic villus samples in first trimester of pregnancy. Prenatal treatment is also possible and pregnancies can be managed by administering dexamethasone to the mother as soon as pregnancy is diagnosed. This suppresses fetal androgen production in genetic females preventing virilization and leading to normal development. Prenatal diagnosis and treatment are highly desirable in families with a positive family history towards birth of a child without features of the disease.