Congenital adrenal hyperplasia (CAH) is a genetic disorder that affects the amount of steroids that the body forms. The most common form of CAH is 21-hydroxylase deficiency (21OHD), which leads to cortisol deficiency. This, in turn, causes the development of mature masculine characteristics in newborn, prepubescent, and grown females and in prepubescent males. 21OHD is known to be caused by the mutation of a specific gene. However, symptom severity among people with 21OHD varies, and adults seem to be less affected than children. This study will examine participants' DNA to determine what other genes may affect the severity of 21OHD and may make the disease milder in adults than in children.