Background: We have screened 309 914 newborns in Yamagata prefecture, Japan
, since 1977 and have detected four patients with phenylketonuria (PKU). We
analyzed the phenylalanine hydroxylase (PAH) gene of the four patients to
study the genetic background in this area and the genotype-phenotype relati
onship in these patients.
Methods: Mutations of the PAH gene were screened by denaturing gradient gel
electrophoresis analysis and the sequences were determined.
Results: Three cases were compound heterozygotes of six different mutations
of the PAH gene and the remaining case was a homozygote. Of the six detect
ed mutations, K115fs is novel, whereas the others have been previously dete
cted among Chinese and/or Japanese patients.
Conclusions: The incidence and genetic basis in Yamagata prefecture was sim
ilar to that of other parts of Japan. Analysis of the genotype is useful to
understand the clinical variation in some families.