An inherited genetic defect is the cause of adrenal hyperplasia, according to Mayo Clinic. To contract the condition, both of a child's parents must have it or be recessive carriers of it.
Adrenal hyperplasia is a congenital autosomal recessive condition, according to the Eunice Kennedy Shriver National Institute of Child Health and Human Development. This means that a child needs to receive defective genetic information from both parents to contract the condition. If both parents carry the gene, there is a 25 percent chance that a child inherits the condition and a 50 percent chance that a child becomes a carrier. If both parents have adrenal hyperplasia, all of their children inherit the condition.
The genetic defect that produces adrenal hyperplasia causes deficiencies in an enzyme produced by the adrenal gland, as the Eunice Kennedy Shriver National Institute of Child Health and Human Development explains. However, the exact enzyme affected and the severity of the deficiency vary from one person to another. Because of the enzyme deficiency, the adrenal glands do not properly produce or regulate hormones, such as androgens, adrenaline and aldosterone. This causes symptoms that vary in severity and range from dehydration, weight loss and shock to early puberty and mild fertility issues. Classic adrenal hyperplasia is typically evident in infancy and more severe than non-classic varieties of the condition that appear later in puberty.