Molecular diagnosis of phenylketonuria in 157 Chinese families and the results of prenatal diagnosis in these families

To the Editor:Phenylketonuria(PKU)is an autosomal recessive genetic disease caused by pathogenic variants in the phenylalanine hydroxylase(PAH)gene encoding phenylalanine hydroxylase,a key enzyme in the metabo-lism of phenylalanine.Early low-phenylalanine diet improves most of the neuropsychological disorders,but it is difficult to be maintained for a long period of time.