[Analysis of short tandem repeats polymorphism in the phenylalanine hydroxylase gene and its application to prenatal gene diagnosis of phenylketonuria].

There is a polymorphic tetranucleotide short tandem repeats (STR) sequence in the intron 3 of the phenylalanine hydroxylase (PAH) gene. The polymorphism of this STR sequence in Chinese was analysed on 36 normal individuals and 16 PKU families. After PCR amplification, the DNA fragments were separated on polyacrylamide sequencing gel and visualized by silver-staining. Seven alleles were identified with frequencies of 0.028, 0.042, 0.014, 0.138, 0.542, 0.208 and 0.028 in normal populations, and 0.016, 0.078, 0.047, 0.312, 0.375, 0.156 and 0.016 in PKU families, and PICs of 0.585 and 0.693, respectively. This polymorphic marker is very useful in quick prenatal gene diagnosis in PKU families, and prenatal gene diagnosis was performed by linkage analysis in two pregnancies at risk.