No abstract available.
Phenylketonurias*

No abstract available.
Phenylketonurias*

OBJECTIVETo establish a hyperphenylalaninemia related genes screening method using Ion Torrent Personal Genome Machine (PGM) for early detection and differential diagnosis of hyperphenylalaninemia (HPA).

METHODSThree children with known HPA mutations and a healthy control were used for setting up the method. Ten children with HPA with known mutations were recruited for validating the method. Ion Ampliseq PCR was used to amplify the 5' and 3' untranslated region, coding sequence, and flanking introns of PAH, GCH1, PTS, QDPR, and PCBD1 genes. After the enrichment with the Ion OneTouch system, the products were sequenced by PGM. Data from the PGM were processed with Torrent Suite v2.2 software package. All variations were confirmed by Sanger sequencing.

RESULTSFor the 4 samples, the PGM output was 94.22 Mb, with approximately 99.5% of reads mapping to the target regions. Among these samples, we detected 74 variations (28 positions) including 6 known mutations. Compared with database and results of Sanger sequencing, 55 (18 positions) polymorphisms and 13 (4 positions) false positive calls were confirmed. For the 10 samples, all the known mutations were successfully identified.

CONCLUSIONIon Torrent PGM sequencing is suitable for screening genetic mutation underlying HPA from the perspective of metabolic pathways, which can meet the clinical demand for individualized diagnosis and treatment.

High-Throughput Nucleotide Sequencing ; methods ; Humans ; Mutation ; Phenylketonurias ; genetics

OBJECTIVETo investigate the type and frequency of mutations in exon 7 of phenylalanine hydroxylase (PAH) gene among children with phenylketonuria (PKU) in Ningxia, China and to provide a basis for the genetic diagnosis and prenatal diagnosis of PKU in this region.

METHODSDirect sequencing of PCR product was performed to analyze the sequences of exon 7 and its flanking introns of 146 PAH alleles in 73 children with typical PKU (39 cases of Hui nationality and 34 cases of Han nationality) in Ningxia.

RESULTSSix mutations were detected, including R243Q (14.4%), R241C (6.8%), IVS7+2T→A (2.7%), L255S (0.7%), G247V (0.7%), and G247R (0.7%). The overall frequency of mutations (missense mutation and splice site mutation) in exon 7 was 26.0% (38/146). The detection rate of R241C mutation was significantly higher in children of Hui nationality than in children of Han nationality(10% vs 3%; P<0.05).

CONCLUSIONSIn Ningxia, R243Q mutation in exon 7 of PAH gene is most common in children with PKU, followed by R241C. The frequency of R241C mutation in exon 7 of PAH gene varies between children with PKU of Hui and Han nationality.

China ; ethnology ; Exons ; Humans ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

The Guthrie bacterial inhibition assay (BIA) tests for elevated phenylalanine (PHE) by measuring B. subtilis growth zone density in an agar medium. Dried blood spots with elevated PHE on initial BIA screening undergo repeat BIA testing and thin-layer chromatography (TLC). Specimens with elevated PHE by TLC or BIA on second-tier testing require recall. To streamline PKU screening and reduce the recall rate, we tested a modified BIA protocol incorporating autoclaving of dried blood spots. Autoclaving improves growth zone appearance and has been previously reported to reduce the number of specimen requiring repeat testing. From June to October 2006, dried blood spot samples with initially elevated PHE were autoclaved at 110°C for 5 min, then retested by BIA. Samples with still-elevated PHE were analyzed by TLC. 1078 of 37,268 samples (2.89%) had initially elevated PHE. After autoclaving, 1036 no longer exhibited elevated PHE decreasing to 42 (0.11%) the number requiring TLC. By comparison, the unmodified algorithm resulted in 3.14% of samples received from July - December 2006 requiring both repeat BIA and TLC testing. We have since modified our PKU screening algorithm to require repeat BIA testing from autoclaved samples prior to TLC analysis. This translates to a significant reduction in time and resources for second-tier testing and follow-up, and prevents stress for the parents of a newborn who would have been recalled unnecessarily.

Agar ; Chromatography, Thin Layer ; Phenylalanine ; Mandatory Testing ; Parents ; Algorithms ; Phenylketonurias

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.
Asian Continental Ancestry Group ; Base Sequence ; DNA ; Genetic Counseling ; Genotype ; Humans ; Leukocytes ; Phenylalanine ; Phenylalanine Hydroxylase ; Phenylketonurias

Tetrahydrobiopterin(BH4) deficiency is a rare type of hyperphenylalaninemia and usually leads to a progressive neurologic deterioration despite early dietary control of blood phenylalanine concentration. We experienced two cases of BH4 deficiency in brother and sister, confirmed by biochemical study of blood and urine. They had suffered from a progressive neurologic illness such as mental retardation, severe hypotonia, seizure, and athetotic movements started at 3 months of their age. Blood amino-acid analysis showed mild hyperphenylalaninemia with elevated urinary neopterin, and reduced urinary biopterin. Their neurologic deteriorations were dramatically improved after replacement of BH4 and dopamine agonist.
Biopterin ; Dopamine Agonists ; Humans ; Intellectual Disability ; Muscle Hypotonia ; Neopterin ; Phenylalanine ; Phenylketonurias* ; Seizures ; Siblings

PURPOSE: The purpose of this study was to evaluate MR findings among patients with phenylketonuria (PKU). MATERIALS AND METHODS: Eleven patients with biochemically documented PKU underwent MR imaging ; In nine, the typical classic form was seen, and two were atypical. We evaluated signal intensity, the distribution of abnormal signal intensity, the extent of brain atrophy, and possible clinical correlation between IQ scores of the patients and abnormal signal intensity. RESULTS: Varying degrees of symmetrical high signal intensity were noted on T2-weighted sequences in the parietal white matter of six patients ; the periventricular deep white matter was most seriously affected, but there was no evidence of brain atrophy. In one advanced case, high signal intensity of both the parietal and frontal lobes was seen on T2-weighted images, and brain atrophy and gyriform enhancementon contrast enhanced T1-weighted images. In five patients, findings were normal. no abnormality was found in the basal ganglia, brain stem or cerebellum. There was no correlation between IQ level and severity of high signal intensity. CONCLUSION: Although MR findings were nonspecific, PKU patients showed symmetrical high signal intensity, predominantly in the peritrigonal region. In the advanced case, the lesion, as seen on T2-weighted images, extended to the periventricular and subcortical white matter.
Atrophy ; Basal Ganglia ; Brain ; Brain Stem ; Cerebellum ; Frontal Lobe ; Humans ; Magnetic Resonance Imaging* ; Phenylketonurias* ; Rabeprazole

OBJECTIVETo delineate the mutation spectrum of phenylalanine hydroxylase (PAH) gene among patients affected with phenylalanine hydroxylase deficiency (PAHD) in Henan Province of China, and to explore the correlation between the genotype and the phenotype.

METHODSA total of 155 affected children were recruited. Potential mutation of the PAH gene were analyzed by direct sequencing. The genotype-phenotype correlation was analyzed by matching the expected and observed phenotypes.

RESULTSOver 72 mutations and 108 genotypes have been identified. There were 7 homozygous mutations, including 1 case with EX6-96A>G/EX6-96A>G, 1 with R241C/R241C, 1 with R413P/R413P, and 4 with R243Q/R243Q. Among these, 6 patients have presented classic PKU phenotypes, except for a R241C/R241C genotype which has led to mild PKU. In 104 patients carrying compound PAH mutations, 52 were classic, 34 were mild and 39 had mild HPA. Patients who were heterozygous for EX6-96A>G/R241C, R243Q/A434D, EX6-96A>G/R413P and EX6-96A>G/ R241C were found with both the classic PKU and mild PKU phenotypes. Common mutations associated with mild HPA have included R53H, R243Q, V399V and H107R. The common mutations associated with mild PKU included R243Q, R241C, EX6-96A>G, and IVS4-1G>A. The prevalent mutations in classic PKU were R243Q, EX6-96A>G and V399V. The consistency between prediction of the biochemical genotype and observed phenotype was 77.78%, especially in classic PKU, the consistency was up to 82.14%. Significant correlations were disclosed between pretreatment levels of phenylalanine and AV sum (r=-0.6729, P < 0.01).

CONCLUSIONThe mutation spectrum of PAH gene in Henan seems to differ from that of other regions. Independent assortment of mutant alleles may result in a complex genotype-phenotype correlation, but the genotypes of PAHD patients have correlated with the phenotype.

Female ; Genotype ; Humans ; Male ; Mutation ; Phenotype ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

This study was to investigate the current status of neonatal screening in China, to further clarify the incidences of hyperphenylalaninemia (HPA) and congenital hypothyroidism (CH). From 2000 to 2007, a total of 17,961,826 newborns had been screened for HPA and 1527 cases were detected, giving a HPA prevalence of 1:11,763. At the same time, 18,284,745 newborns had also been tested for CH, with 8918 cases being detected (1:2050). It is remarkable that the mean number of newborns screened per year had increased 5 times between 2000 and 2007. In Shanghai, 116,000 newborns were screened using tandem mass spectrometry and 6 different were detected. The overall prevalence of an inborn errors of metabolism identified was 1 in 5800 healthy newborns, with hyperphenylalaninemia being the most common. Neonatal screening had developed rapidly in China in recent years, and a pilot study using tandem mass spectrometry has been started. The biggest challenge is still to increase coverage to the entire country, especially in the mid-western area.
China ; Congenital Hypothyroidism ; diagnosis ; Humans ; Infant, Newborn ; Neonatal Screening ; Phenylketonurias ; diagnosis