Amniotic 17-alpha hydroxyprogesterone and HLA typing for the prenatal diagnosis of 21-alpha hydroxylase deficiency--congenital adrenal hyperplasia.

We have investigated a family with one child affected with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. Prenatal determination of 17-alpha hydroxyprogesterone (17OHP) in amniotic fluid (AF) and HLA typing of amniotic fibroblasts from a pregnancy at risk showed that the fetus was not affected. A healthy cousin with HLA haplotypes identical to those of the proposita (only one being identical by descent) had a normal plasma level of 17OHP. The prenatal diagnosis of a fetus affected with 21-hydroxylase deficiency CAH may be established by the determination of 17OHP in AF. This is a relatively quick procedure that can be confirmed by the HLA genotype, and is mandatory in families with a parent homozygous for an HLA haplotype and in certain recombinant haplotypes in the fetus.