Detection of IVS4+1G gt;A mutation in phenylalanine hydroxylase gene in North of Iran using PCR-sequencing

Background and aims: Phenylketonuria (PKU) is an autosomal recessive disorder of phenylalanine (Phe) metabolism. Mutations in the phenylalanine hydroxylase (PAH) gene are the main reason for the incidence of PKU. To date, more than 1180 variants have been detected in the PAH gene. Given that the distribution pattern of mutations in the PAH gene is specific to each population, the present study was conducted to detect exon 4 mutations and adjacent flanking regions of the PAH gene in northern Iran. Methods: This is a descriptive cross-sectional study, in which 24 unrelated PKU patients in Taleghani Hospital in Gorgan were enrolled for a one-year period. After extraction of genomic DNA from leukocytes, identification of exon 4 mutations and adjacent flanking regions was performed using polymerase chain reaction (PCR) and sequencing techniques. Results: In this study, IVS4+1G gt;A mutation was detected in one allele (2.08%) among 48 alleles. Moreover, IVS4+47C gt;T and IVS3-22C gt;T polymorphisms were observed in 12 alleles (25%) and eight alleles (16.7%), respectively. Conclusion: In the present study, IVS4+1G gt;A mutation was only found in 2% of chromosomes. Hence, different mutations are responsible for PKU disease in the north of Iran, and further studies are recommended to identify all mutations in the PAH gene in the region.