Girl babies with Congenital Adrenal Hyperplasia (CAH) have male sex organs. The condition is caused by a lack of a certain enzyme in the adrenal gland. It is the most common cause of atypical genitalia in newborns.
The condition is inherited and passed on by an autosomal recessive gene. Autosomal recessive means that each parent carries one copy of the gene and passes on the gene to the child. Carrier parents have a 1 in 4 chance of having a child with this condition with each pregnancy. Girl babies with the condition have atypical genitalia. Boy babies don't.
In some cases, the mother of a child with this condition can be given medicines during pregnancy to lessen the effects of the enzyme deficiency if the baby is female.
Another type of CAH is called salt-losing. This is very serious and often fatal. It causes an electrolyte collapse in the newborn. Treatment is available if diagnosed early. Boys and girls are equally affected.
Other, rarer enzyme problems can also cause CAH in either boy babies or girl babies.