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  • 1
    Electronic Resource
    Electronic Resource
    Combined tetrahydrobiopterin-phenylalanine loading test in the detection of partially defective biopterin synthesis (1984)
    Springer
    European journal of pediatrics 142 (1984), S. 126-129 
    Details
    ISSN: 1432-1076
    Keywords: Hyperphenylalaninemia ; Biopterin deficiency ; Tyrosine ; Atypical phenylketonuria ; Abnormal EEG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Deficiency in the synthesis of biopterin causes neonatal hyperphenylalaninemia. We report a 10-year-old girl of normal appearance with a partial defect in biopterin synthesis, normal intelligence and normal serum phenylalanine levels (95 μmol/l) (1.6 mg/dl). During her 1st year of life srum phenylalanine levels were 250 μmol/l (4 mg/dl) and phenylalanine loading performed at 6 months and 1 year of age was not followed by an increase in serum tyrosine. At 9 years of age she had developed a severely abnormal EEG with focal spike activity but no observable clinical abnormalities. Determination of urinary pterins showed abnormal low levels of biopterin and high levels of neopterin. Phenylalanine loading combined with oral administration of tetrahydrobiopterin (BH4) was followed by a normal increase in serum tyrosine and a normal decrease in serum phenylalanine. Considering the importance of BH4 for the synthesis of dopamine, catecholamines, and serotonin we suggest that these cases should be followed carefully. If neurological symptoms appear, e.g., epilepsy, it may be worthwhile to consider treatment with BH4 and neurotransmitter precursors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445592
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  • 2
    Electronic Resource
    Electronic Resource
    Variability in clinical expression of Menkes syndrome (1988)
    Springer
    European journal of pediatrics 148 (1988), S. 132-135 
    Details
    ISSN: 1432-1076
    Keywords: Menkes syndrome ; Genetic heterogeneity ; Copper therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Six patients with Menkes syndrome are described, who differ from patients with the classical form of Menkes syndrome because of their longer survival; some of them also exhibited a milder manifestation of symptoms. Based on the present data and a summary of seven case reports describing Menkes patients with long survival, it may be possible to divide these patients into two subgroups:one group of severely affected patients with long survival and another group of very mildly affected patients with late onset of symptoms. Perhaps only the latter represents a true subgroup of Menkes syndrome. The possible benefits of copper therapy are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00445920
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  • 3
    Electronic Resource
    Electronic Resource
    Increased neurotransmitter biosynthesis in phenylketonuria induced by phenylalanine restriction or by supplementation of unrestricted diet with large amounts of tyrosine (1988)
    Springer
    European journal of pediatrics 148 (1988), S. 238-245 
    Details
    ISSN: 1432-1076
    Keywords: Attention ; Dopamine ; PKU ; Serotonin ; Tyrosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Seven phenylketonuria (PKU) patients aged 15–24 years were allowed unrestricted diet for 3 weeks. Three of these patients performed well on unrestricted diet according to visual reaction time variability (RTv 50–100 ms) and did not show significant changes when returning to the phenylalanine-restricted diet (RTv 70–100 ms). Neither did the concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF) change significantly. Four of the patients, however, performed rather poorly (RTv 120–220 ms) on unrestricted diet and improved significantly (P〈0.03) when the diet was restored (RTv 70–150 ms). The improvements were accompanied by significant (P〈0.01 and P〈0.02) increases (mean 52% and 109%) in CSF levels of HVA and 5-HIAA. Five PKU patients aged 15–23 years were allowed unrestricted diet or unrestricted diet supplemented with various amounts of tyrosine (106–194 mg/kg per 24 h). Two of these patients performed very well on unrestricted diet (RTv 60 ms) and showed little change when the unrestricted diet was supplemented with tyrosine (RTv 70 ms and 80 ms). The three other patients, who performed rather poorly (RTv 120–220 ms), improved significantly (P〈0.03) when the unrestricted diet was supplemented with tyrosine (RTv 70–140 ms). HVA in CSF increased significantly (P〈0.01) with the tyrosine supplement when the amount exceeded a threshold of approximately 80 mg/kg per 24 h. The simultaneous increase in CSF level of 5-HIAA showed a positive correlation (r=0.90; P〈0.02) with the increase in HVA concentration suggesting a functional interrelation between the dopaminergic and the serotoninergic nervous systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441411
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular biology of phenylketonuria (1987)
    Springer
    European journal of pediatrics 146 (1987), S. A5 
    Details
    ISSN: 1432-1076
    Keywords: Phenylketonuria ; Phenylalanine hydroxylase gene mutations ; Oligonucleotide probes ; Haplotype analysis ; Hyperphenylalaninemia phenotypes ; Prenatal diagnosis ; Heterozygote detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442048
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  • 5
    Electronic Resource
    Electronic Resource
    Decreased vigilance and neurotransmitter synthesis after discontinuation of dietary treatment for phenylketonuria in adolescents (1985)
    Springer
    European journal of pediatrics 144 (1985), S. 17-20 
    Details
    ISSN: 1432-1076
    Keywords: Attention ; Serotonin ; Dopamine ; PKU
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Four adolescent or young adult patients with phenylketonuria were examined before and after discontinuation of dietary treatment. Plasma and CSF phenylalanine concentrations increased about two-fold in three patients. In these patients the CSF concentration of the dopamine and serotonin metabolites homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) decreased markedly; 5-HIAA to extremely low values. The reaction time variability increased in these patients. In the fourth case plasma phenylalanine levels, CSF HVA and 5-HIAA levels, and reaction time variability were essentially unchanged. The relationship between reaction time variability and the CSF 5-HIAA level for all four patients could be presented as a linear function. However, a causal relationship is still unproven. These preliminary findings demonstrate that there may be hazards in the discontinuation of dietary treatment, even in adolescents or young adults, for neurotransmitter metabolism and mental function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00491918
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  • 6
    Electronic Resource
    Electronic Resource
    Normal excretion of urinary acid mucopolysaccharides in a boy with iduronate sulphatase deficiency, Hunter phenotype and α1-antitrypsin deficiencydeficiency (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 572-575 
    Details
    ISSN: 1432-1076
    Keywords: Hunter syndrome ; α1-antitrypsin deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The chance coincidence of an X-linked disorder with an autosomal recessive disorder in one child is described. The child had the clinical phenotype of a mucopolysaccharidosis and the activity of iduronate sulphatase was almost absent. Furthermore, fibroblasts from a typical Hunter patient were unable to correct the patient's fibroblasts. However, three 24 h urine samples collected at 18–36 months of age showed a nearly normal excretion of acid mucopolysaccharides. The boy died in liver coma at 3 years of age. Autopsy showed cirrhosis of the liver and changes in liver tissue consistent with α1-antitrypsin deficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02429071
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  • 7
    Electronic Resource
    Electronic Resource
    A prevalent missense mutation in Northern Europe associated with hyperphenylalaninaemia (1991)
    Springer
    European journal of pediatrics 150 (1991), S. 347-352 
    Details
    ISSN: 1432-1076
    Keywords: Phenylketonuria ; Hyperphenylalaninemia ; Phenylalanine hydroxylase ; Gene mutations ; DNA amplification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A missense mutation has been identified in the phenylalanine hydroxylase (PAH) gene of a Danish patient with hyperphenylalaninaemia (HPA). An A-to-G transition at the second base of codon 414 results in the substitution of Cys for Tyr in the mutant PAH protein. In in vitro expression studies, the Tyr414-to-Cys414 mutant construct produced a protein which exhibited a significant amount of normal PAH enzyme activity, which is consistent with both in vitro and in vivo measurements of PAH activity in HPA patients. Population genetic studies reveal that this mutation is present on 50% of mutant haplotype 4 chromosomes in the Danish population. Together with the previously reported codon 158 mutation, these two mutant alleles comprise over 90% of all mutant haplotype 4 chromosomes in the Northern Europcan population. Thus, two allele-specific oligonucleotide probes can detect most mutant haplotype 4 chromosomes in Northern Europe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955938
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  • 8
    Electronic Resource
    Electronic Resource
    Phenotyping of phenylketonuric patients by oral phenylalanine loading (1996)
    Springer
    European journal of pediatrics 155 (1996), S. 523-525 
    Details
    ISSN: 1432-1076
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955198
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  • 9
    Electronic Resource
    Electronic Resource
    The influence of mutations on enzyme activity and phenylalanine tolerance in phenylalanine hydroxylase deficiency (1996)
    Springer
    European journal of pediatrics 155 (1996), S. S6 
    Details
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Mutations ; Phenylalanine tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The phenylalanine hydroxylase (PAH) deficiency trait is heterogeneous with a continuum of metabolic phenotypes ranging from classical phenylketonuria (PKU) to mild hyperphenylalaninaemia (MHP). More than 200 mutations in the PAH gene are associated with PAH deficiency. From theoretical considerations or in vitro expression studies each mutation has a particular influence on enzyme activity, which explains the variation in dietary tolerance for phenylalanine (Phe). This paper gives a summary of the effect of each type of mutation on PAH activity and illustrates how the combination of mutations (the genotype) is associated with the Phe tolerance (the metabolic phenotype). Mutations within a population generally include a few prevalent mutations and a high number of rare mutations. The particular distribution of mutations implies that many PAH-deficient patients carry the same mutation combination, enabling the establishment of genotype-phenotype correlations by comparing clinical parameters in patients with identical genotypes. Because certain mutations always cause MHP irrespective of the mutation on the second allele, mutation typing of hyperphenylalaninaemic neonates will differentiate between PKU and MHP. In addition, genotyping will provide a tool for precise diagnosis of the metabolic phenotype of the neonate with PKU and thereby permit earlier implementation of dietary therapy better tailored to each individual patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00014253
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  • 10
    Electronic Resource
    Electronic Resource
    In vivo assessment of mutations in the phenylalanine hydroxylase gene by phenylalanine loading: characterization of seven common mutations (1995)
    Springer
    European journal of pediatrics 154 (1995), S. 551-556 
    Details
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Hyperphenylalaninaemia ; Phenylalanine hydroxylase ; Phenylalanine loading ; Genotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mutations in the gene encoding phenylalanine hydroxylase (PAH) cause persistent hyperphenylalaninaemia. To date, more than 200 point mutations and microdeletions have been characterized. Each mutation has a particular quantitative effect on enzyme activity and recessive expression of different mutant alleles results in a marked interindividual heterogeneity of metabolic and clinical phenotypes. In this paper we demonstrate how a simple clinical test can be used to evaluate the correlation between mutation genotype and phenylalanine metabolism. In hyperphenylalaninaemic patients with known PAH mutation genotype, we have investigated phenylalanine turnover in vivo by measuring the ability to eliminate a test dose of l-phenylalanine. All patients could be considered functionally hemizygous for one of their mutant alleles by carrying on the other allele a mutation that is known to completely abolish PAH activity and encode a peptide with no immunoreactivity. Seven mutations (R408W, IVS-12nt1, R261Q, G46S, Y414C, A104D, and D415N) were characterized by oral phenylalanine loading, each mutation being represented by at least three patients. The elimination profile determined for a 3-day period provides a measure to compare residual activity of the mutant proteins and to assign each mutation to a particular metabolic phenotype. The established relation between genotype and phenotype may enable prediction of the severity of the disease by genotype determination in the newborn period. This will aid in the management of hyperphenylalaninaemia and may improve prognosis. Conclusion The possibility of predicting the residual enzyme activity by DNA analysis performed already in the newborn period allows the prompt implementation of a diet that is adjusted to the degree of PAH deficiency. This may improve management and prognosis of hyperphenylalaninaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02074833
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