Typing of families with classical phenylketonuria using three alleles of the Hindlll linked restriction fragment polymorphism, detectable with a phenylalanine hydroxylase cDNA probe

A human phenylalanine hydroxylase cDNA clone was isolated from a human liver cDNA library. The size of the cDNA insert is approximately 2.4 kb and appears to be a near full length copy of a phenylalanine hydroxylase mRN A. This cDN A was used to probe for Hindlll restriction enzyme polymorphisms in heterozygote typing of families with phenylketonuria. The use of three alleles of this polymorphism, as opposed to the two alleles as previously described, increases the informativity for typing - and therefore also for prenatal diagnosis -in certain families from 75% to 100%.