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J Zschocke

Publications and source records attributed to J Zschocke.

At least 55 records · Page 3Linked to original sources
PubMed2000

Effect of genotype on changes in intelligence quotient after dietary relaxation in phenylketonuria and hyperphenylalaninaemia.

BACKGROUND: Associations between genotype and intellectual outcome in patients with phenylketonuria are complicated because intelligence is influenced by many variables, including environmental factors and other genetic determinants. Intellectual changes with age, both on and after relaxation of diet, vary within the patient population. This study aims to determine whether a significant association exists between genotype and change in intelligence after relaxation of diet. METHODS: 125 patients with hyperphenylalaninaemia and phenylketonuria whose diet was relaxed after 8 years of age. Verbal, performance, and full scale intelligence quotients at 8, 14, and 18 years were expressed as standard deviation scores (IQ-SDS), and genotype as predicted residual enzyme activity (PRA) of phenylalanine hydroxylase. RESULTS: IQ-SDS at 8, 14, and 18 years were significantly below normal; no association was found between PRA and IQ-SDS. Significant reductions in verbal and full scale IQ-SDS occurred between 8 and 14 years and 8 and 18 years. There was a significant association between PRA and the reduction in verbal, performance, and full scale IQ between these years. Multiple regression analysis of 18 year results, using 8 year results as covariates, supported the association between PRA and IQ-SDS; after adjustment for phenylalanine control, both up to and after the age of 8 years, the full scale IQ-SDS at 14 and 18 years was 0.15 higher for each 10% increase in PRA. CONCLUSIONS: Genotype might be useful in predicting the likelihood of intellectual change in patients with hyperphenylalaninaemia and phenylketonuria whose diet is relaxed after the age of 8 years.

Adolescent↗
PubMed2000

Mutation analysis in glutaric aciduria type I.

Glutaric aciduria type 1 (GA1), resulting from the genetic deficiency of glutaryl-CoA dehydrogenase (GDH), is a relatively common cause of acute metabolic brain damage in infants. Encephalopathic crises may be prevented by carnitine supplementation and diet, but diagnosis can be difficult as some patients do not show the typical excretion of large amounts of glutaric and 3-hydroxyglutaric acids in the urine. We present a rapid and efficient denaturing gradient gel electrophoresis (DGGE) method for the identification of mutations in the glutaryl-CoA dehydrogenase (GCDH) gene that may be used for the molecular diagnosis of GA1 in a routine setting. Using this technique, we identified mutations on both alleles in 48 patients with confirmed GDH deficiency, while no mutations were detected in other patients with clinical suspicion of GA1 but normal enzyme studies. There was a total of 38 different mutations; 27 mutations were found in single patients only, and 21 mutations have not been previously reported. Fourteen mutations involved hypermutable CpG sites. The commonest GA1 mutation in Europeans is R402W, which accounts for almost 40% of alleles in patients of German origin. GCDH gene haplotypes were determined through the analysis of polymorphic markers in all families, and three CpG mutations were associated with different haplotypes, possibly reflecting independent recurrence. The high sensitivity of the DGGE method allows the rapid and cost efficient diagnosis of GA1 in instances where enzyme analyses are not available or feasible, despite the marked heterogeneity of the disease.

Brain Diseases, Metabolic, Inborn↗
PubMed2000

Progressive infantile neurodegeneration caused by 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency: a novel inborn error of branched-chain fatty acid and isoleucine metabolism.

We report a novel inborn error of metabolism identified in a child with an unusual neurodegenerative disease. The male patient was born at term and recovered well from a postnatal episode of metabolic decompensation and lactic acidosis. Psychomotor development in the first year of life was only moderately delayed. After 14 mo of age, there was progressive loss of mental and motor skills; at 2 years of age, he was severely retarded with marked restlessness, choreoathetoid movements, absence of directed hand movements, marked hypotonia and little reaction to external stimuli. Notable laboratory findings included marked elevations of urinary 2-methyl-3-hydroxybutyrate and tiglylglycine without elevation of 2-methylacetoacetate, mild elevations of lactate in CSF and blood, and a slightly abnormal acylcarnitine profile. These abnormalities became more apparent after isoleucine challenge. Enzyme studies showed absent activity of 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) in the mitochondrial oxidation of 2-methyl branched-chain fatty acids and isoleucine. Under dietary isoleucine restriction, neurologic symptoms stabilized over the next 7 months.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1999

Glutaryl-CoA dehydrogenase deficiency presenting as 3-hydroxyglutaric aciduria.

Two siblings who were found to have deficiency of glutaryl-CoA dehydrogenase were identified by the presence of large amounts of 3-hydroxyglutaric acid in the urine. Patients with this disease, termed glutaric acidemia or glutaric acidemia Type I, usually present with large amounts of glutaric acid in the urine, and amounts of 3-hydroxyglutaric acid found are less. Patients were ataxic and dystonic. Intelligence was normal. 3-Hydroxyglutaric acid in the urine was quantified by organic acid analysis via gas chromatography mass spectrometry (GCMS) and by stable isotope-dilution (internal standard) GCMS. Glutaryl-CoA dehydrogenase activity in cultured fibroblasts was found to be 2% of the control level. The nature of the mutations was identified, and both patients were found to be compound heterozygotes for R227P, which changed an arginine to a proline, and E365K, which changed a glutamate to a lysine.

Amino Acid Metabolism, Inborn Errors↗
PubMed1999

Phenylketonuria mutations in Germany.

We report the spectrum of mutations and associated modified haplotypes in patients with phenylketonuria living in Germany. A total of 546 independent alleles was investigated, including 411 of German and 65 of Turkish descent. Mutations were identified for 535 PKU alleles (98%) and there were 91 different mutations. The most common mutation was R408W on 22% of alleles. Two mutations, IVS12+1G-->A and IVS10-11G-->A accounted for just under 10% of alleles, whereas the remaining mutations were found at relative frequencies of 6% or less; 43 mutations were observed once only. IVS10-11G-->A was the most common mutation (38% of alleles) in the subgroup of patients of Turkish descent. Modified haplotypes were determined from the analysis of four silent mutations, three diallelic restriction fragment length polymorphisms, a variable number of tandem repeats minisatellite and a short tandem repeat microsatellite in the phenylalanine hydroxylase gene, showing that a considerable proportion of mutations must have recurred in independent founders; other mutations may have changed chromosomal haplotype backgrounds by gene conversion. The spectrum of PKU mutations in Germany reflects the history of a heterogenous Central European population living at the crossroads of migration throughout the centuries.

Exons↗
PubMed1999

Large heterozygous deletion masquerading as homozygous missense mutation: a pitfall in diagnostic mutation analysis.

The clinical use of molecular analyses in recessive disorders relies on the exact characterization of both mutant alleles in the affected patient. This can be problematic when only part of the gene is examined or when relevant DNA alterations are not recognized by standard methods. We present a child in whom phenylketonuria was apparently caused by homozygosity for the mutation E390G in exon 11 of the phenylalanine hydroxylase (PAH) gene. However, the clinical severity of the disease was not quite as mild as expected, the mutation was not identified in the father despite confirmed paternity, and the paternal allele showed a highly unusual pattern of polymorphic markers in the PAH gene. Presence of a large deletion involving exons 9, 10 and 11 of the phenylalanine hydroxylase gene was confirmed by long-range PCR. Diagnostic DNA analyses should include a comprehensive examination of the whole relevant gene in the patient and confirmation of carrier status in both parents.

DNA Mutational Analysis↗
PubMed1999

Glutaric aciduria type I: from clinical, biochemical and molecular diversity to successful therapy.

The biochemical hallmark of glutaric aciduria type I (GA I) due to glutaryl-CoA dehydrogenase deficiency is the accumulation of glutaric acid, and to a lesser degree of 3-hydroxyglutaric and glutaconic acids. Abnormal metabolites vary from gross organic aciduria to only slightly or intermittently elevated or even normal excretion of glutaric acid, making the diagnosis sometimes difficult. Close to 100 pathogenic mutations have been identified in the gene encoding glutaryl-CoA dehydrogenase. Specific mutations correlate with low or no excretion of glutaric acid, but there appears to be no correlation between genotype and clinical phenotype. GA I causes unique age- and location-specific neuropathological sequelae. Starting in the second half of gestation, maturation of the frontal and temporal cortex is hindered, leading to the characteristic appearance of frontotemporal atrophy. Between 6 and 18 months of age, relatively mild neurological symptoms may become exacerbated by fever or a catabolic state in the course of common infections or routine immunizations, by fasts required for surgery, or by minor head injuries. Putamen and caudate are destroyed, resulting in a permanent movement disorder that is similar to cerebral palsy and ranges from extreme hypotonia to choreoathetosis to rigidity with spasticity. Recently, the underlying pathophysiology could be delineated to an environmentally triggered age- and location-specific overstimulation of the NMDA 2B receptor subtype. Current therapy prevents brain degeneration in more than 90% of affected infants who are treated prospectively. Without treatment, more than 90% of affected children will develop severe neurological disabilities. Recognition of this disorder before the brain has been injured is essential to treatment. GA I may be recognized in routine neonatal screening performed with tandem mass spectrometry by an elevation of glutarylcarnitine. Where this is not done, timely diagnosis depends on the recognition of relatively nonspecific physical findings such as hypotonia, irritability, macrocephaly, on the detection of suggestive abnormalities in neuroimaging and on quantitative urinary organic acid analysis by gas chromatography--mass spectrometry.

Animals↗
PubMed1998

Diagnosis and management of glutaric aciduria type I.

Glutaric aciduria type I (GA1) is a preventable cause of acute brain damage in early childhood, leading to a severe dystonic-dyskinetic disorder that is similar to cerebral palsy and ranges from extreme hypotonia to choreoathetosis to rigidity with spasticity. Degeneration of the putamen and caudate typically occurs between 6 and 18 months of age and is probably linked to changes in metabolic demand caused by normal maturational changes and superimposed catabolic stress. Recognition of this biochemical disorder before the brain has been injured is essential to outcome. Diagnosis depends upon the recognition of relatively non-specific physical findings such as hypotonia, irritability and macrocephaly, and on performance of urine organic acid quantification by gas chromatography--mass spectrometry or selective searches of urine or blood specimens by tandem mass spectrometry for glutarylcarnitine. The diagnosis may also be suggested by characteristic findings on neuroimaging. In selected patients diagnosis can only be reached by enzyme assay. Specific current management by the authors of this paper includes pharmacological doses of L-carnitine, as well as dietary protein restriction. Metabolic decompensation must be treated aggressively to avoid permanent brain damage. Multicentre studies are needed to establish best methods of diagnosis and optimal therapy of this disorder.

Amino Acid Metabolism, Inborn Errors↗
PubMed1998

A European multicenter study of phenylalanine hydroxylase deficiency: classification of 105 mutations and a general system for genotype-based prediction of metabolic phenotype.

Phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP) are allelic disorders caused by mutations in the gene encoding phenylalanine hydroxylase (PAH). Previous studies have suggested that the highly variable metabolic phenotypes of PAH deficiency correlate with PAH genotypes. We identified both causative mutations in 686 patients from seven European centers. On the basis of the phenotypic characteristics of 297 functionally hemizygous patients, 105 of the mutations were assigned to one of four arbitrary phenotype categories. We proposed and tested a simple model for correlation between genotype and phenotypic outcome. The observed phenotype matched the predicted phenotype in 79% of the cases, and in only 5 of 184 patients was the observed phenotype more than one category away from that expected. Among the seven contributing centers, the proportion of patients for whom the observed phenotype did not match the predicted phenotype was 4%-23% (P<.0001), suggesting that differences in methods used for mutation detection or phenotype classification may account for a considerable proportion of genotype-phenotype inconsistencies. Our data indicate that the PAH-mutation genotype is the main determinant of metabolic phenotype in most patients with PAH deficiency. In the present study, the classification of 105 PAH mutations may allow the prediction of the biochemical phenotype in >10,000 genotypes, which may be useful for the management of hyperphenylalaninemia in newborns.

Alleles↗
PubMed1997

Phenylketonuria and the peoples of Northern Ireland.

The comparison of regional patterns of recessive disease mutations is a new source of information for studies of population genetics. The analysis of phenylketonuria (PKU) mutations in Northern Ireland shows that most major episodes of immigration have left a record in the modern genepool. The mutation 165T can be traced to the Palaeolithic people of western Europe who, in the Mesolithic period, first colonised Ireland. R408W (on haplotype 1) in contrast, the most common Irish PKU mutation, may have been prevalent in the Neolithic farmers who settled in Ireland after 4500 BC. No mutation was identified that could represent European Celtic populations, supporting the view that the adoption of Celtic culture and language in Ireland did not involve major migration from the continent. Several less common mutations can be traced to the Norwegian Atlantic coast and were probably introduced into Ireland by Vikings. This indicates that PKU has not been brought to Norway from the British Isles, as was previously argued. The rarity in Northern Ireland of IVS12nt1, the most common mutation in Denmark and England, indicates that the English colonialization of Ireland did not alter the local genepool in a direction that could be described as Anglo-Saxon. Our results show that the culture and language of a population can be independent of its genetic heritage, and give some insight into the history of the peoples of Northern Ireland.

Archaeology↗
PubMed1996

Clinical course, early diagnosis, treatment, and prevention of disease in glutaryl-CoA dehydrogenase deficiency.

BACKGROUND: Glutaryl-CoA dehydrogenase deficiency (GDD) is a recessively inherited neurometabolic disorder associated with encephalopathic crises and severe extrapyramidal symptoms. Treatment regimens including glucose and electrolyte infusions during acute illnesses, oral carnitine supplementation and/or a low-protein or lysine-restricted diet have been recommended, but their efficacy has been documented only on an anecdotal basis. SUBJECTS AND METHODS: We conducted a retrospective analysis of 57 patients with proven GDD-relating appearance and severity of neurological disease to age and clinical status at diagnosis, glutaric acid levels in body fluids, and different treatment regimens. RESULTS: Thirty-six patients were diagnosed after the onset of neurological disease (symptomatic group), twenty-one before (presymptomatic group). Carnitine levels were found to be reduced in all patients at diagnosis. In the symptomatic group, macrocephaly had been present around birth and was followed by rapid postnatal head growth in 70% of the children. The patients often showed symptoms such as hypotonia, irritability, and jitteriness followed by an acute encephalopathic crisis occurring on average at 12 months of age. Common neuroimaging findings included frontotemporal atrophy, subependymal pseudocysts, delayed myelination, basal ganglia atrophy, chronic subdural effusions and hematomas. In four patients the latter two findings were initially misinterpreted as resulting from child abuse. Other important misdiagnoses in older siblings who were affected and went undiagnosed include postencephalitic cerebral palsy, dystonic cerebral palsy and sudden infant death syndrome. Metabolic treatment did not convincingly improve the neurological disease, although it may have prevented further deterioration. Symptomatic treatment with baclofen or benzodiazepines was effective in reducing muscle spasms. Children in the presymptomatic group were diagnosed because of familiarity for the disease (n = 13), macrocephaly and/or additional minor neurological signs in infancy (n = 6), or acute encephalopathy, which was fully reversible after prompt treatment (n = 2). After diagnosis, all children were treated with oral carnitine, fluid infusion during intercurrent illnesses and, in addition, a diet was started in 13 of the 21 children. All 21 children except one (born prematurely at 31 weeks) have continued to develop normally up to now. Mean age at report is 6.3 years with a range from 6 months to 14.8 years. In older patients, the neuroradiological changes, present in infancy as in the symptomatic patients, became less prominent and in one girl disappeared. CONCLUSIONS: In presymptomatic children with GDD, the onset of neurological disease can be prevented by vigorous treatment of catabolic crises during illnesses together with carnitine supplementation. The importance of dietary therapy remains unclear and needs further evaluation. The potential treatability of GDD calls for increased attention to early presenting signs in order to recognize the disorder and to initiate treatment before the onset of irreversible neurological disease.

Adolescent↗
PubMed1995

A fluorescent multiplex ARMS method for rapid mutation analysis.

The amplification refractory mutation system (ARMS) is a powerful technique for the identification of mutations. We present a modification of this technique involving coamplification of normal and mutant alleles with primers that differ in length by three to five bases. Fluorescent labelling allows exact sizing of the amplification products on an automated DNA fragment analyser. We have used the fluorescent multiplex ARMS method for the identification of common phenylketonuria mutations in Northern Ireland (R408W, 165T and F39L) together with the analysis of a polymorphic short tandem repeat site at the human phenylalanine hydroxylase locus. This provides an efficient and inexpensive first step for diagnostic mutation analysis in our population.

Alleles↗