The symptoms of 21 hydroxylase deficiency seen in a child depends on the severity of the enzyme defect and the sex of the child. Boys with a severe defect will show symptoms at about ten days of age with vomiting, dehydration and weight loss - also known as the 'salt-losing crisis'.
Girls with a severe defect will have ambiguous (non-feminised) genitalia at birth due to the effect of androgen over production in the developing baby. Unless treated promptly these girls will also develop a 'salt-losing crisis'. Boys and girls with a mild defect will have symptoms later in childhood with signs of androgen excess - tall stature, enlargement of penis or clitoris, and early development of pubic hair but no salt-losing crisis.