A novel large deletion(exons 12,13)and a missense mutation(p.G46R)in the PAH in a Japanese patient with phenylketonuria

Background:Phenylketonuria(PKU)is caused by a defect in phenylalanine hydroxylase(PAH).More than 500 mutations have been reported for the gene encoding PAH.However,approximately l%-5%of these include large deletions and large duplications that cannot be detected by conventional methods.Methods:In this report we tried to fully characterize a PAH-deficient patient.The patient was a 2-year-old Japanese boy who was diagnosed with classical PKU at the time of neonatal screening,which was confirmed by the tetrahydrobiopterin-loading test.PCR-related direct sequencing and multiplex ligation-dependent probe amplification(MLPA)were used to analyze of the PAH of the patient.Results:Using PCR-related direct sequencing method,we could detect only a heterozygous novel missense mutation:p.136G>C(p.G46R).A second mutation was detected by MLPA.The patient was heterozygous for a novel large deletion of exons 12 and 13:c.1200-?_1359+?del(EX12_13del).For genetic counseling,an accurate genetic diagnosis is often necessary.Conclusions:Through a combination of MLPA and conventional methods,the success rate of PAH mutation identification can be close to 100%.

Analysis of EX5del4232ins268 and EX5del955 PAH gene mutations in Ukrainian patients with phenylketonuria

Phenylketonuria(PKU)is an autosomal recessive metabolic disorder caused by deficiency of phenylalanine hydroxylase(PAH).The major molecular defects causing PKU are missense mutations of PAH gene.Large deletions of exon 5(EX5del955 and EX5del4232ins)were first reported by the Czech study and were later found also in the Polish,Slovak,Slovenian and Italian PKU-patients.These observations demonstrate the existence of a common subset of this mutation predominantly among Central European populations of Slavic descent.That is why we suggest that EX5del1955 and EX5del4232ins268 mutations might be frequent causes of PKU in Ukrainian patients.EX5del955 and EX5del4232ins268 mutations were analyzed in 106 unrelated PKU patients negative for PAH gene mutations on one or both alleles from our previous analysis.The simultaneous detection of EX5del4232ins268 and EX5del955 mutations was performed by PCR amplification of mutant alleles.EX5del955 mutation was not detected in the Ukrainian patients.This relative alleles frequency of EX5del4232ins268 mutation in the Ukrainian PKU population was determined as 1,66%.Our findings can be the one more evidence of Central European Slavic origin of EX5del4232ins268 mutation,suggested previously.This finding is important for the improvement of DNA diagnosis necessary for the management of PKU patients from Ukraine.