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What is Congenital Adrenal Hyperplasia (CAH)?
Congenital adrenal hyperplasia (CAH) is a genetic disorder affecting the adrenal glands which lie on the top of the kidneys. The adrenal glands do not function normally due to a mutation in the gene coding for the enzyme, adrenal steroid 21-hydroxylase. Due to this lack, the adrenal glands produce too little cortisol or aldosterone and too much androgen. CAH affects normal growth and development in children and some forms can even be life-threatening.
Currently there is no cure for CAH though people can lead a fairly normal life with available treatment.
CAH is mainly inherited in an autosomal recessive pattern where both the parents carry a mutated gene resulting in the child being affected. Affected children inherit an abnormal copy of the gene from both parents. There is a 25% chance of every child inheriting the disease from parents who carry a copy of the mutated gene.
Globally, CAH affects 1 in 10,000 people with the most common form being 21 hydroxylase deficiency. Non-classic form of CAH may be more common affecting 1 in 1000 people in the general population.
- 21-hydroxylase deficiency
- 17a-hydroxylase deficiency
- 11-Beta hydroxylase deficiency
- congenital lipoid adrenal hyperplasia
- p450 oxidoreductase deficiency
Symptoms of CAH depend on the gene affected and the level of enzyme being produced.
Classic CAH is the most severe form of the disease and usually presents during infancy:
- Water loss or dehydration
- Low circulating blood volume (hypovolemia)
- Low blood pressure
- Circulatory collapse in extreme cases
Non-classic CAH is milder and does not present with any symptoms at birth. The condition becomes evident only in later childhood or adolescence. Males and females are equally affected and some of the symptoms include:
- Absent or irregular periods in females
- Masculine characteristics
- Early appearance of pubic hair
CAH is usually picked up easily during newborn screening for infants. If one sibling is affected, the family should be able to avail prenatal testing through amniocentesis or chorionic villus sampling (CVS).
Doctors usually diagnose CAH in babies and children with a physical exam, blood and urine tests and finally a genetic testing for confirmation of the exact genotype.
- Corticosteroids to replace cortisol
- Mineralocorticoids to replace aldosterone and maintain potassium balance
- Salt supplements to retain salt
If there is a known case of CAH in the family, it is absolutely essential for closest female relatives like siblings, uncles, aunts and cousins to test for carrier status.
If a woman with a carrier status is pregnant, prenatal test is essential to determine if the fetus has the disease mutation.