Genetics of 21-hydroxylase deficiency: Clinical presentation should guide the investigation.

A young couple applied for preconception counseling because of a case of congenital adrenal hyperplasia in the family. They were concerned about their risk of giving birth to a child with classic congenital adrenal hyperplasia. The case presented here demonstrates the complexity of the genetics of 21-hydroxylase deficiency and the way the clinical presentation should guide the genetic inquiry.