Congenital Adrenal Hyperplasia: Causes & Prevention

Causes of CAH are due to chromosome mutations. There are two types of CAH, both due to different enzymes which exist in the person’s chromosome. The first enzyme, enzyme 21-hydroxylase, causes 90% of the disease, and affects both hormones, glucocorticoid and mineralocorticoid. Both of these hormones are secreted from the outer adrenal gland, or adrenal cortex. These persons have the ‘salt-wasting’ form of CAH. They present with low sodium, low blood volume, low blood pressure, and high potassium levels. The second type, is due to enzyme 11-hydroxylase, and only 10% of patients with CAH have this type. These people have an accumulation of metabolites with mineralocorticoid properties which causes high blood pressure. Therefore, simple blood pressure measurements can differentiate the two different types of CAH. The Classic enzyme 11-hydroxylase CAH occurs more frequently in Moroccan Jews, while Non-Classic enzyme 21-hydroxylas CAH occurs most frequently in Ashkenazi Jews, and In Hispanic, Slavic and Italian populations.
The disease may be prevented. As the disease is genetic if either partner has the CAH gene, the children may also have it. The amniotic fluid can be tested to determine any chromosomal deficiencies. An unborn baby can be treated with maternal dexamethasone. Birth weight, length, head circumference and congenital anomalies of affected infants whose mothers are treated during pregnancy are comparable to those infants who do not have CAH; thus, reducing either the incidence or severity of the disease.
Additionally, many states and foreign countries now test all infants at birth for this genetic defect, simultaneously testing for other genetic type diseases. The reason for newborn screening is that mainly in boys, who have no outward sign of the disease, the mortality from "adrenal crisis" is high, and this could be entirely prevented by early diagnosis and medical treatment