The Study of DNA Mutations of Phenylketonuria in Koreans

PURPOSE: Phenylketonuria(PKU) is an inborn error of metabolism and a genetic disorder resulting from a deficiency of phenylalanine hydroxylase(PAH) and decreased activity of tetrahydrobiopterin(BH4).In this study the correlation between the DNA mutation and clinical manifestations was investigated and PAH DNA mutations were compared bewteen Asian and Caucasian populations. METHODS: DNA was isolated from peripheral leukocytes. The PAH gene was amplified by Polymerase Chain Reaction(PCR) and the sequence was analyzed with Multiplex Ligation-dependent Probe Amplification(MLPA). RESULTS: We characterized the PAH gene of 102 independent Korean patients with PKU. PAH nucleotide sequence analysis revealed 44 different mutations, including 10 novel mutations comprising 9 missense mutations(N207D, K95del, A447P, G344D, P69S, S391I, A202T, G103S, and I306L) and 1 novel splice-site variant mutation(IVS10-3C>G). R243Q was the most prevalent mutation in this study. A259T has not previously been reported in Asian populations, but we found that this mutation had a frequency of 10.1% in our study. Furthermore, the genotypes of BH4 responsive patients were analyzed and were divided into two groups: BH4 medication-only group and BH4 medication with diet therapy group. In the BH4 medication-only group and BH4 medication with diet therapy group, R241C was the most common mutation. CONCLUSION: Novel mutations in the PAH gene of PKU patients are still being discovered. Additional information as to the frequency of mutations in the tetrahydrobiopterine responsive gene is also accumulating. We anticipate that knowledge of these PKU gene mutations will assist the diagnosis, genetic counseling, and therapeutic treatment of PKU patients in future.

Clinical Phenotype of Different Hyperphenylalaninemia Patients / 实用儿科临床杂志

Objective To explore clinical characteristics of phenylalanine hydroxylase(PAH) deficiency in differential diagnosis among hyperphenylalaninemia(HPA) patients and compare the responses to diet treatment in HPA patients.Methods Tetrahydrobiopterin(BH4,20 mg/kg) loading test or combined phenylalanine(Phe,100 mg/kg) and BH4 loading test was carried out among 44 HPA patients.The urine pterine profile analysis and dihydropteridine reductase(DHPR) activity in dry blood filter spot were analyzed simultaneously.Electroencephalogram(EEG) and average full scale development quotient(DQ) were performed in all patients.PAH deficiency patients were given low Phe diet treatment to decrease Phe level for 120-360 ?mol/L and followed up their Phe tolerance.Results Twelve BH4 responsive PAH deficiency patients were diagnosed who were 7 males and 5 females,mean age was 7.8 months.Their metabolic phenotype was moderate or mild HPA.Diet control could decrease Phe level among BH4 deficiency patients but not prevent their neural damage and their EEG abnormal rate was higher.BH4 responsive patients had higher DQ than others and their Phe tolerance increased during diet treatment.Conclusions BH4 responsive PAH deficiency patients can obtain better purpose with diet recipe.The differential diagnosis for BH4 deficiency shall be carried out in all patients with HPA as soon as possible.