Overview
Congenital adrenal hyperplasia (CAH) is a group of rare inherited autosomal recessive disorders characterized by a deficiency of one of the enzymes needed to make specific hormones. CAH effects the adrenal glands located at the top of each kidney. Normally, the adrenal glands are responsible for producing three different hormones: 1. corticosteroids, which gauge the body’s response to illness or injury; 2. mineralocorticoids, which regulate salt and water levels; and 3. androgens, which are male sex hormones. An enzyme deficiency will make the body unable to produce one or more of these hormones, which in turn will result in the overproduction of another type of hormone precursor in order to compensate for the loss.
The most common cause of CAH is the absence of the enzyme 21-hydroxylase. Different mutations in the gene responsible for 21-hydroxylase result in different levels of the enzyme, producing a spectrum of effects. CAH due to 21-hydroxylase deficiency is responsible for 95% of all cases of CAH and is broken down further into two subcategories: classical CAH, which can be sub-divided into the salt-losing form or the simple-virilizing form, and non-classical CAH. Classical CAH is by far the more severe form and can result in adrenal crisis and death if not detected and treated. Non-classical CAH is milder, and may or may not present symptoms. Since the absence of 21-hydroxylase makes these individuals unable to make the hormone cortisol and, in the case of salt-losing CAH, aldosterone, the body produces more androgens which cause a variety of symptoms such as abnormal genital development in infant girls. There are other much rarer forms of CAH as well, including 11-Beta hydroxylase deficiency, 17a-hydroxylase deficiency, 3-Beta-hydroxysteroid dehydrogenase deficiency, congenital lipoid adrenal hyperplasia and p450 oxidoreductase deficiency which all present different symptoms. Although CAH is not curable, as long as patients receive adequate care and treatment, they can go on to lead normal lives.