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E R Baumgartner

Publications and source records attributed to E R Baumgartner.

At least 19 recordsLinked to original sources
PubMed2006

The first case of 3-methylcrotonyl-CoA carboxylase (MCC) deficiency responsive to biotin.

3-Methylcrotonylglycinuria is an inborn error of leucine catabolism with an autosomal recessive pattern of inheritance that results from a deficiency of 3-methylcrotonyl-CoA carboxylase (MCC). We report on a nine-year-old boy with severe psychomotor retardation who developed infantile spasms at the age of three weeks. Urine analysis at the age of two years revealed massive 3-methylcrotonylglycinuria and 3-hydroxyisovaleric aciduria suggesting MCC deficiency. Carnitine serum levels were decreased. Biotin therapy led to a dramatic decrease in the frequency of seizures, disappearance of hypsarrhythmia, and near normalisation of organic aciduria. Four months later a protein-restricted diet was introduced in addition and the boy remained clinically and metabolically stable. However, severe psychomotor delay persisted, and the seizures partially reoccurred. Biochemical findings showed partial MCC deficiency in cultured fibroblasts. Molecular genetic studies revealed a heterozygote missense mutation, MCCA-R385S, converting arginine to serine in a highly conserved region of the MCCA gene. This is the first patient with MCC deficiency caused by a heterozygote mutation and who demonstrated a substantial and sustained clinical and biochemical response to therapeutic doses of biotin. Sadly, this patient again also demonstrates that the main determinant of the outcome of even easily treatable metabolic diseases is timely diagnosis.

Biotin↗
PubMed2003

Partial response to biotin therapy in a patient with holocarboxylase synthetase deficiency: clinical, biochemical, and molecular genetic aspects.

We report the clinical course and biochemical findings of a 10-year-old, mentally retarded girl with late-onset holocarboxylase synthetase (HCS, gene symbol HLCS) deficiency and only partial response to biotin. On treatment, even with an unusually high dose of 200mg/day, activities of the biotin-dependent mitochondrial carboxylases in lymphocytes remained below 50% of the mean control values. Not only urinary 3-hydroxyisovaleric acid excretion has been persistently elevated, but also plasma and, with even higher concentrations, cerebrospinal fluid 3-hydroxyisovaleric acid have not normalized. The unusual and insufficient response of this patient to biotin treatment can be explained by the effect of the combination of the common HLCS allele IVS10 +5 g>a on one chromosome and a truncating mutation on the other. This case illustrates mechanisms involved in the genotype-phenotype correlation that unequivocally exists in HCS deficiency.

Age of Onset↗
PubMed2002

Perioperative management of a child with very-long-chain acyl-coenzyme A dehydrogenase deficiency.

Very-long-chain acyl-coenzyme A dehydrogenase deficiency is an inborn error of fatty acid metabolism. The clinical presentation of this disease in children is either a severe form with onset of symptoms in the first months of life, cardiomyopathy, metabolic acidosis, myopathy and a high mortality, or a less severe form manifesting mainly with hypoglycaemia. Perioperative fasting and (even emotional) stress can trigger metabolic decompensation through the altered metabolism of endogenous fatty acids resulting in hypoglycaemia, acute cardiac and hepatic dysfunction and rhabdomyolysis. We report the perioperative management of a 9-year-old boy suffering from the severe form of this disease who underwent circumcision. Metabolism was kept stable in this child by using a glucose--electrolyte infusion throughout the perioperative period to avoid the biochemical consequences of fasting and a benzodiazepine--opioid technique combined with regional anaesthesia to minimize the stress response. Considering reports about a possible interference of propofol with fatty acid oxidation and to avoid the unnecessary administration of fatty acids, propofol should not be used in these patients.

Anesthesia, Conduction↗
PubMed2001

Mutation analysis of the MCM gene in Israeli patients with mut(0) disease.

Three novel mutations (IVS8+3a --> g, N219Y, and E414X) were identified in 6 unrelated patients with mut(0) methylmalonic aciduria. The presence of a wild-type along with rearranged fragments in homozygotes for the IVS8+3a --> g mutation may contribute to their later age of onset (3-11 months of age). Nonetheless, delayed onset was not associated with better neurological outcome and prolonged survival. The large number of undiagnosed dead sibs in most families suggests that the disease is largely underdiagnosed in this region.

Amino Acid Metabolism, Inborn Errors↗
PubMed2001

Clinical and neuropsychological outcome in 33 patients with biotinidase deficiency ascertained by nationwide newborn screening and family studies in Austria.

UNLABELLED: Newborn screening for biotinidase deficiency (BD) provides prevention of neurological sequelae in patients with low residual enzyme activity by early treatment with oral biotin substitution. Screening 1.1 million newborns in Austria and consecutive family studies led to the identification of 21 patients with profound BD (residual activity <10%) (incidence: 1:59,800) and to 12 patients with partial BD (residual activity 10%-30%) (incidence 1:89,700). Application of an HPLC assay using the natural substrate biocytin allowed exact quantification of extremely low residual biotinidase activities and thus subdivision of patients with profound BD into a group with a residual activity 0%-1% of normal activity (n = 5) and >1%-<10% (n = 16) respectively. Evaluation of clinical and neuropsychological outcome showed that only patients with a biotinidase activity < 1% (n = 3/5) exhibited characteristic clinical symptoms within the first weeks of life, while five patients with a residual activity of 1.2%-4.6% did not develop clinical symptoms even when not treated until 3.5 21 years. In all patients with residual activity <10% and biotin substitution within the first weeks of life, neuropsychological outcome was normal, while abnormal in three out of five patients tested for IQ and treated after the age of 3.5 years. In five out of nine patients with poor compliance or delayed or no treatment, visual and brainstem auditory evoked potentials were measured and were within age-related normal values. All patients with partial BD available for follow-up remained clinically and neuropsychologically asymptomatic without treatment at ages 2.5 10 years. CONCLUSION: The incidence of biotinidase deficiency in Austria is comparable to other European countries. Subdivision of the group of patients with profound biotinidase deficiency suggests that only patients with residual activities < 1% are prone to develop clinical symptoms early in life, while patients with residual activities >1% may remain asymptomatic even without treatment, as do patients with partial deficiency. Moderate mental retardation might represent a possible manifestation of cerebral dysfunction in patients with profound biotinidase deficiency.

Adolescent↗
PubMed2001

Biotinidase determination in serum and dried blood spots--high sensitivity fluorimetric ultramicro-assay.

A miniaturized quantitative biotinidase assay has been developed using biotin 6-amidoquinoline as substrate and the 100-fold enhanced fluorescence of 6-amidoquinoline measured using apolar solvents. Amidoquinoline is measured after deproteinization by ethanol/acetone using individual standardisation and solvent resistant microtiter plates. The assay was optimized for end point determinations of biotinidase activities in serum and for newborn screening using dried blood spots. Serum activities obtained are closely correlated with values obtained using a quantitative validation method (r=0.96). Analytical sensitivity is around 2% of the mean activity (7.01+/-1.92 nmol/min/ml, mean+/-SD) of a healthy control population. With dried blood spots, a close correlation with values obtained using the Wallac-test kit (r=0.92) was found. Biotinidase activities of a healthy population of 651 newborns amount to 0.2429+/-0.07 nmol/min/ml blood. The analytical sensitivity is close to 1% of the mean activity.

Adolescent↗
PubMed2001

The molecular basis of human 3-methylcrotonyl-CoA carboxylase deficiency.

Isolated biotin-resistant 3-methylcrotonyl-CoA carboxylase (MCC) deficiency is an autosomal recessive disorder of leucine catabolism that appears to be the most frequent organic aciduria detected in tandem mass spectrometry-based neonatal screening programs. The phenotype is variable, ranging from neonatal onset with severe neurological involvement to asymptomatic adults. MCC is a heteromeric mitochondrial enzyme composed of biotin-containing alpha subunits and smaller beta subunits. Here, we report cloning of MCCA and MCCB cDNAs and the organization of their structural genes. We show that a series of 14 MCC-deficient probands defines two complementation groups, CG1 and 2, resulting from mutations in MCCB and MCCA, respectively. We identify five MCCA and nine MCCB mutant alleles and show that missense mutations in each result in loss of function.

Alleles↗
PubMed2000

Biotin and biocytin uptake into cultured primary calf brain microvessel endothelial cells of the blood-brain barrier.

The uptake of biotin and the closely related biocytin was characterized in primary cultures of calf brain microvessel endothelial (CBME) cells. Biotin uptake was found to be Na(+)-gradient dependent and independent of changes in the membrane potential. Concentration dependence revealed a single saturation mechanism with a K(m) of 47 microM and a V(max) of 101 pmol/min/mg. Inhibition studies demonstrated dependence on metabolic energy and the necessity for a free carboxyl group for transport activity. The anticonvulsants primidone and carbamazepine had no inhibitory effect. Biotin uptake into CBME cells is a secondary active, electroneutral, saturable and specific process. Biocytin which accumulates in biotinidase deficiency, a human congenital disorder, did not inhibit biotin uptake and was not transported into these cells. The presence of human serum with normal biotinidase activity significantly reduced biotin uptake by about 50%. Further, added biocytin was hydrolyzed to biotin, which accumulated intracellularly but to a lesser extent than added free biotin. Biotin uptake after addition of plasma of biotinidase-deficient patients was not different from that in the presence of normal serum. These results indicate that the absence of biotinidase activity in serum does not reduce blood-brain barrier transport of biotin.

Amidohydrolases↗
PubMed2000

mut0 methylmalonic acidemia: eleven novel mutations of the methylmalonyl CoA mutase including a deletion-insertion mutation.

Methylmalonic aciduria (MMA) is an autosomal-recessive disorder caused by inadequate function of methylmalonyl-CoA mutase (MCM), a nuclear-encoded, mitochondrial enzyme that uses adenosylcobalamin as a cofactor. Biochemical cell studies have delineated phenotypic variants: mut(0) phenotypes in which there is no detectable enzymatic activity and mut- phenotypes in which there is residual cobalamin-dependent activity. Mutation screening in MMA has led to the detection of 30 disease-specific mutations. In 14 patients with the mut(0) phenotype we found 11 novel mutations (K54X, A137V, F174S, 620insA, G203R, Q218H, A535P, H627R, 2085delG and 2270del4/ins5), 6 of them homozygous, consisting of 1 nonsense, 6 missense, 1 splice site, and 3 frame shift mutations. The position in relation to different functional domains in MCM allow for an interpretation of the identified mutations. Hum Mutat 16:179, 2000.

Gene Deletion↗
PubMed2000

3-methylcrotonyl-CoA carboxylase deficiency in an infant with cardiomyopathy, in her brother with developmental delay and in their asymptomatic father.

UNLABELLED: Three affected members of one family, each with a different clinical presentation of isolated biotin-resistant 3-methylcrotonyl-CoA carboxylase (MCC) deficiency are described. The index patient presented at 7 weeks of age with feeding difficulties, sweating and tachypnoea. Echocardiography showed a severely dilated left ventricle with minimal contractility. MCC deficiency was suspected on the basis of elevated urinary excretion of 3-hydroxyisovalerate and 3-methylcrotonylglycine. Deficiency of MCC activity was found in lymphocytes and fibroblasts (ca. 2% of mean normal). Serum carnitine was low (free 10 micromol/l). Some other possible causes of cardiomyopathy were excluded. Cardiomyopathy was not improved by carnitine therapy. The healthy father and a developmentally delayed brother also had MCC deficiency. Both also had decreased serum carnitine concentrations, but without cardiac involvement. Dilatative cardiomyopathy as predominant symptom in isolated MCC deficiency has not been described before, although severe carnitine deficiency is a common finding in MCC deficiency. It is not clear whether this is a coincidental association. CONCLUSION: In order to understand the phenotypic spectrum of this rare disorder, cardiac evaluation should be made in patients with 3-methylcrotonyl-CoA carboxylase deficiency. Biochemical and clinical investigations have also to be performed in their parents and siblings. In addition, 3-methylcrotonyl-CoA carboxylase deficiency should be included in the differential diagnosis of dilatative cardiomyopathy.

Adult↗
PubMed1999

Metabolic stroke in isolated 3-methylcrotonyl-CoA carboxylase deficiency.

A mildly retarded infant with failure to thrive developed hypoglycaemia, focal seizures, respiratory failure and hemiparesis during a febrile episode at the age of 16 months. A brain scan was initially normal and showed hemilateral focal edema and gliosis at later stages. 3-Methylcrotonyl-CoA carboxylase deficiency was suggested by elevated urinary excretion of 3-hydroxyisovaleric acid and 3-methylcrotonylglycine, and confirmed by enzyme assays. The patient was treated with protein restriction and carnitine and remained stable during the following 5 years. Hemiparesis and some developmental delay persisted. In acute focal brain disease, metabolic disorders must be considered. 3-Methylcrotonyl-CoA carboxylase deficiency adds to the list of possible causes of "metabolic stroke".

Amino Acid Metabolism, Inborn Errors↗
PubMed1999

Identification and characterization of mutations in patients with holocarboxylase synthetase deficiency.

Holocarboxylase synthetase deficiency (HCS) is an autosomal recessive disorder characterized by metabolic ketoacidosis, abnormal urine organic metabolites, and dermatitis. These symptoms are improved by pharmacological doses of biotin. In this study, we have analyzed seven patients with HCS deficiency found in European and Middle Eastern countries by using reverse transcription/polymerase chain reaction/single-stranded conformation polymorphism and a sequencing analysis. Although we had previously reported that two mutations were frequent in Japanese patients, no frequent mutations were found in the patients analyzed in this study. Seven novel mutations were identified in the cDNA of the patients; these included three missense mutations, two single-base deletions that resulted in a termination codon, a three-base in-frame deletion, and a 68-bp deletion. A new polymorphism C1121T was also identified in four alleles. A transient expression study demonstrated that the HCS activities of three missense mutations and one amino acid deletion were 1%-14% that of wild-type cDNA; in contrast, the activities of the two single-base deletions followed by a termination codon and Asp571Asn were nearly undetectable. These data suggest that a variety of mutations is responsible for decreasing HCS activity and that the aspartate residue at amino acid position 571 may be crucial for the catalytic activity of HCS.

Carbon-Nitrogen Ligases↗
PubMed1999

Holocarboxylase synthetase deficiency: report of a case with onset in late infancy.

A case of holocarboxylase synthetase (HCS) deficiency of late-infantile onset is presented and compared with the common manifestations in previously reported patients. Our patient had her first episode at 20 months followed by recurrent episodes of metabolic acidosis with ketolactic acidosis responding dramatically to a short trial of biotin and thiamin. The main clinical findings were metabolic acidosis with alteration in consciousness and respiration, which are in accordance with findings in earlier reported patients with both neonatal-onset and infantile-onset forms of HCS deficiency. The diagnosis of HCS deficiency was made only at the age of 5.5 years during a metabolic work-up when organic acid analysis was performed. This revealed elevated urinary excretion of the characteristics metabolites, 3-hydroxypropionate, 3-hydroxyisovalerate and methylcitrate, suggesting multiple carboxylase deficiency (MCD). MCD was demonstrated in fibroblasts of our patient, but only when the cells were grown in a medium with a very low biotin concentration of 10(-10) mol/L. Kinetics studies of reactivation of deficient propionyl-CoA carboxylase activity with biotin in intact fibroblasts revealed a midly decreased reactivation rate and only a 3-5 times higher biotin requirement as compared with controls. These findings are in accordance with a mild form of HCS deficiency. This child responded to 10 mg/day of biotin with normal lymphocyte carboxylase activities and adequate school performance at 10 years of age.

Age of Onset↗
PubMed1999

Transcobalamin II deficiency with methylmalonic aciduria in three sisters.

Transcobalamin II (TC II) is a plasma protein that binds vitamin B12 (cobalamin, Cbl) and facilitates cellular Cbl uptake by receptor-mediated endocytosis. In autosomal recessive TC II deficiency, intracellular Cbl deficiency results in an early onset of megaloblastic anaemia that may be accompanied by neurological abnormalities. Inadequate treatment may lead to neurological abnormalities. We describe three sisters, the daughters of first cousins of Moroccan origin, with TC II deficiency requiring continuous and long-term vitamin B12 treatment. The diagnosis was suspected from the finding of low unsaturated vitamin B12 binding capacity and confirmed by absence of detectable TC II by radioimmunoassay and by inability of cultured fibroblasts to synthesize TC II.

Cells, Cultured↗
PubMed1999

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency.

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established.

Acyl-CoA Dehydrogenase, Long-Chain↗
PubMed1999

Relationship between kinetic properties of mutant enzyme and biochemical and clinical responsiveness to biotin in holocarboxylase synthetase deficiency.

Holocarboxylase synthetase (HCS) deficiency is a metabolic disorder that causes a biotin-responsive multiple carboxylase deficiency. We analyzed the kinetic properties of seven mutant HCS proteins. Two of these enzymes harbored mutations within the putative biotin-binding region of HCS and showed elevated Km values for biotin compared with that of the wild-type form (Km mutant; Gly581Ser: 45 times, delThr610: 3 times). The remaining five mutations (Arg183Pro, Leu216Arg, Leu237Pro, Val333Glu, and Val363Asp) were located outside the biotin-binding region. The enzymes containing these mutations showed normal or low Km values for biotin (non-Km mutant). Symptoms of patients who have the non-Km, mutants, as well as those of patients who have the Km, mutants, responded to biotin therapy. This is probably because the Km value for biotin of normal HCS is higher than the physiologic concentration of biotin in human cells. The Vmax values of all mutant HCS proteins were considerably decreased, but to a variable degree. The responsiveness to biotin supplementation of propionyl-CoA carboxylase activity in cultured cells bearing the mutations correlated well with the degree of reduction in the Vmax of HCS. Patients who have mutant HCS proteins with lower Vmax showed poorer clinical and biochemical responses to biotin therapy. These observations suggest that the reduction of Vmax is an essential factor for pathophysiology and prognosis of HCS deficiency under treatment with large amounts of biotin. The determination of HCS genotype can be valuable for characterizing the clinical phenotype in HCS deficient patients.

Biotin↗