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Chronic subdural hematoma, as an initial manifestation of glutaric aciduria type-1.

A 10-month-old male with glutaric aciduria type-1 (GA-1) is reported. This patient showed frequent partial motor seizures, irritability, and involuntary movements, including oral dyskinesia at the age of 3 months. On admission, magnetic resonance (MR) scanning revealed a chronic subdural hematoma and widening of the bilateral insular cisterns. Urine organic acid analysis showed marked excretion of glutaric acid, 3-hydroxy glutaric acid and glutaconic acid, suggesting GA-1. Removal of the subdural hematoma was effective for the irritability but not for the extrapyramidal signs. This is the first report of a subdural hematoma as an initial symptom in a patient with GA-1. However, the complication of subdural fluid collection in GA-1 is not rare. To our knowledge, of 29 patients with GA-1 who underwent computed tomographic or MR scans, 5 had subdural fluid collection. Disproportional hypoplasia of the temporal lobes may be a suggestive etiology of subdural fluid collection/chronic subdural hematoma.

Amino Acid Metabolism, Inborn Errors↗

Treatment of the cbl B form of methylmalonic acidaemia with adenosylcobalamin.

A 30-month-old girl was found to have the cbl B mutant form of methylmalonic aciduria by complementation analysis of fibroblasts. She was unresponsive to hydroxycobalamin and was treated with intramuscular adenosylcobalamin (AdoCbl), the deficient coenzyme, at a dose of 1 mg/24h during a period of clinical stability. Serum cobalamin increased from 770 to 54 200 pg/ml. Mean urinary methylmalonic acid excretion was 409 mg/24 h prior to therapy. There was a transient fall in methylmalonic acid excretion during the first 5 days of therapy (range 167-245 mg/24h) followed by a rise in excretion toward pretreatment levels (range 317-485 mg/24h) during the second week of AdoCbl treatment. There was no change in plasma ammonia, glycine or serum bicarbonate level. We interpret the failure of this child to have a sustained and clinically significant response to AdoCbl as indicating that AdoCbl did not reach or enter the mitochondria intact, or in some other way was unavailable as a coenzyme for the methylmalonyl CoA mutase apoenzyme.

Amino Acid Metabolism, Inborn Errors↗

Analysis of naturally occurring and site-directed mutations in the argininosuccinate lyase gene.

Argininosuccinic aciduria is an inborn error of metabolism due to the genetic deficiency of argininosuccinate lyase. In order to determine the molecular basis for the disease, RNA isolated from cultured skin fibroblasts derived from four unrelated patients was reverse-transcribed and amplified using the polymerase chain reaction and the products were cloned and sequenced. Three single base missense mutations were identified: Arg111----Trp, Gln286----Arg, and Arg193----Gln. One single base amber mutation was identified at Gln454. One mutation involved a 13-base pair deletion within exon 13, and it was noted that the majority of the mature RNA derived from this allele was deleted for the entire exon rather than containing the exon with the 13 bases deleted. A final mutation was observed in which exon 2 was deleted from the mature RNA. The molecular basis for this deletion was not determined. Of the eight potential mutations present in the four cell lines studied, six mutations were identified and further data indicate that the remaining two unidentified mutations were different from those identified. Two site-directed mutations were created in the cDNA, Lys51----Asn and His89----Gln, and these were expressed in yeast. The Lys51 mutation caused an approximate 2-fold reduction in activity and the His89 mutation resulted in an approximate 10-fold reduction in activity. The combination of determination of naturally occurring mutations and the study of the effect of site-directed mutations on the activity of argininosuccinate lyase provide insight into the amino acid residues critical to the function of the enzyme.

Amino Acid Sequence↗

Fetal polycystic kidney disease associated with glutaric aciduria type II: an inborn error of energy metabolism.

The findings of hyperechoic and enlarged fetal kidneys on routine antenatal ultrasonography is a non-specific finding that alerts the physician to a differential diagnosis of various genetic and non-genetic disorders, including fetal polycystic disease and Beckwith-Wiedeman syndrome. Detection of fetal or neonatal polycystic kidneys should alert the physician to the possibility of an associated lethal autosomal recessive inborn error of fatty acid metabolism known as multiple acyl-CoA-dehydrogenase defect (MADD). We report a case of fetal nephromegaly associated with rare inborn error of MADD. This case highlights the need for appropriate laboratory investigation of hyperechoic, enlarged fetal kidneys, and neonatal polycystic disease. The association of MADD with postnatally diagnosed polycystic disease of the kidney has been reported. The antenatal detection of nephromegaly followed by the subsequent postnatal diagnosis of MADD has not been previously reported. MADD should be considered in the differential diagnosis of this antenatal finding. Appropriate diagnostic procedures should be conducted, either pre- or postnatally, in order that appropriate genetic counseling may be provided for this autosomal recessively inherited disorder.

Acyl-CoA Dehydrogenases↗

Inhibition of brain glutamate decarboxylase by glutarate, glutaconate, and beta-hydroxyglutarate: explanation of the symptoms in glutaric aciduria?

Glutaric aciduria is a disorcer of lysine, tryptophan, and hydroxylysine metabolism characterized by intermittent metabolic acidemia, dystonia, athetosis and mental retardation. It is due to a recessively inherited deficiency of glutaryl-CoA dehydrogeanse, the enzyme(s) which catalyze the dehydrogenation of glutaryl-CoA to glutaconyl-CoA and decarboxylation of the latter to crotonyl-CoA. Abnormal quantities of glutaric, beta-hydroxyglutaric, and glutaconic acids are found in the urine of these patients. The nature of the movement disorder prompted study of the effects of the abnormally excreted metabolites on brain glutamate decarboxylase, an enzyme implicated in the pathogenesis of Huntington's chorea. Glutamate decarboxylase activity was examined in rat and rabbit brain acetone powders, stabilized with pyridoxal phosphate and glutathione. Glutarate, beta-hydroxyglutarate, and glutaconate were competitive inhibitors of this emzyme, Ki values being 1.3 X 10(-3) mol/l, 2.5 X 10(-4) mol/l, respectively. This inhibition may explain the neurological accompaniments of this syndrome.

Amino Acid Metabolism, Inborn Errors↗

Dicarboxylic aciduria due to medium chain acyl CoA dehydrogenase defect. A cause of hypoglycemia in childhood.

Dicarboxylic aciduria was found during hypoglycemic episode in a 14 months old girl. Her brother had died at the age of 4 years during febrile illness. A ketogenic diet induced in this patient a severe hypoglycemia. Urinary organic acid profile exhibited abnormal excretion of the C6-C10 dicarboxylic acids (adipic-suberic-sebacic) and related metabolites (5 hydroxyhexanoic, hexanoylglycine, suberyl glycine). This pattern suggested a defect in fatty acids beta oxidation. Plasma carnitine values was within control limits. Similar clinical findings and urinary organic acids excretion have been described in 6 patients since the initial case of Gregersen. Enzymatic studies on cultivated fibroblasts from our patient showed a defect in medium chain CoA dehydrogenase. The treatment of this disease consists of glucose infusion during attacks and prevention of fasting. This rare disease must be considered in a child with non ketotic hypoglycemia or Reye's syndrome.

Acyl-CoA Dehydrogenases↗

Dilated cardiomyopathy due to type II X-linked 3-methylglutaconic aciduria: successful treatment with pantothenic acid.

A case of dilated cardiomyopathy in a young boy secondary to type II 3-methylglutaconic aciduria is described. A metabolic cause for his dilated cardiomyopathy was suspected because of the development on the electrocardiogram of an unusual "camel's hump" shape of the T waves, and of progressive thickening with increasing echogenicity of the left ventricular wall. He initially improved on digoxin treatment, but did not maintain the response with conventional dietary treatment for this condition. Supplementation with L-carnitine was associated with rapid deterioration in cardiac state, and may be contraindicated in this condition. At a point when the patient was moribund, large doses of pantothenic acid, a precursor of coenzyme A, produced a dramatic and sustained improvement in myocardial function and in growth, neutrophil cell count, hypocholesterolaemia, and hyperuricaemia, which suggests that limitation of availability of coenzyme A is a fundamental pathological process in this condition. The clinical improvement has been maintained for 13 months, and myocardial function is now nearly normal. Oral pantothenol, unlike pantothenic acid, is not efficacious.

Amino Acid Metabolism, Inborn Errors↗

[Glutaric aciduria type 1: phenotypic variability. Report of 6 patients].

We report six patients with glutaric aciduria type 1 in four families. The patients had marked clinical variability, even within families. Three of the patients studied were normal until the onset of neurologic abnormalities, that presented as an encephalitis-like illness in the first year of age. One patient had an early and important developmental delay, but never suffered an encephalopathic crisis. Two patients have intellectual preservation; one of them has a mild tremor and choreoathetosis since the first year of age, and the other had only two afebrile seizures in infancy and no other neurologic signs. Three patients are severely handicapped, with a severe dystonic-dyskinetic disorder and unable to even sit. All the six patients have macrocephaly and in all the computed tomography showed enlarged CSF spaces and sulcal separation over the frontal and temporal lobes. Urine organic acids study of all patients showed large quantities of glutaric acid.

Adult↗

Glutaconyl-CoA is the main toxic agent in glutaryl-CoA dehydrogenase deficiency (glutaric aciduria type I).

Despite early diagnosis and treatment, 35% of the patients with glutaric aciduria type I (GA I) develop severe neurologic damage. Glutaric acid and 3-hydroxyglutaric acid have been suspected to cause neurodegeneration. Lately, this has been questioned, however. We postulate that glutaconyl Coenzyme A (glutaconyl-CoA) is responsible for brain damage. Chemically, glutaconyl-CoA is an analogue of acrylyl-CoA, the parent substance of the extremely reactive class of acrylates. It is expected to react spontaneously with sulfhydryl groups, thus modifying membranes, disturbing enzyme functions and trapping glutathione. Enhanced production of glutaconyl-CoA together with lack of glutathione precipitates brain damage. Such a mechanism is supported by three findings. (1) The addition product of glutaconyl-CoA to cysteine is present in small amounts in normal human urine. (2) Reaction of methacrylyl-CoA with free sulfhydryl groups has been reported previously in a patient with 3-hydroxyisobutyryl CoA deacylase deficiency. (3) Glutathione has been found to be decreased in homozygous glutaryl-CoA dehydrogenase-deficient knock-out mice.

Acyl Coenzyme A↗

Seven novel mutations in mut methylmalonic aciduria.

Methylmalonic aciduria (MMA) is an autosomal recessive inborn error of metabolism that results from functional defects in methylmalonyl CoA mutase (MCM), a nuclear-encoded, mitochondrial enzyme that uses the vitamin B12 derivative, adenosylcobalamin (AdoCbl) as a cofactor. To date, 23 mutations have been identified at the MUT locus on the short arm of chromosome 6, causing the mut forms of MMA (mut complementation group; mut MMA, McKusick #251000). We now report seven novel mutations. Three were found inmut0 patients: R228Q (c759G-->A) was found as a heterozygous change; G312V (c1011G-->T) and 346delL (c1112delCTT) were both found as homozygous changes. Four mutations were found in mut patients: A191E (c648C-->A) and V633G (c1974T-->G) were found in the same patient; 684insL (c2128insCTC) and L685R (c2130T-->G) were both found as homozygous changes. The recent modelling of the human methylmalonyl CoA mutase allowed for an interpretation of the identified mutations.

Alleles↗

3-Methylcrotonyl-CoA carboxylase deficiency: mutation analysis in 28 probands, 9 symptomatic and 19 detected by newborn screening.

Isolated 3-methylcrotonyl-CoA carboxylase (MCC) deficiency is an autosomal recessive disorder that appears to be the most frequent organic aciduria detected in tandem mass spectrometry (TMS)-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, encoded by MCCA and MCCB, respectively. We report mutation analysis in 28 MCC-deficient probands, 19 of whom were asymptomatic newborns detected by TMS newborn screening, and nine presented with clinical symptoms. Ten have mutations in MCCA, and 18 in MCCB. We identified 10 novel MCCA and 14 novel MCCB mutant alleles including missense, nonsense, frameshift and splice site mutations, and show that three of the missense mutations result in severely decreased MCC activity when expressed in MCC-deficient cell lines. Our data demonstrate no clear correlation between genotype and phenotype suggesting that factors other than the genotype at the MCC loci have a major influence on the phenotype of MCC deficiency.

Alleles↗

Two missense point mutations in different alleles in the 3-hydroxy-3-methylglutaryl coenzyme A lyase gene produce 3-hydroxy-3-methylglutaric aciduria in a French patient.

Two novel point mutations in the 3-hydroxy-3-methylglutaryl coenzyme A lyase gene were found in a French patient with double heterozygous 3-hydroxy-3-methylglutaric aciduria. Amplification by reverse transcriptase-polymerase chain reaction of the mRNA using five different pairs of oligonucleotides produced no differences in the fragments amplified with respect to the control. Single-strand conformation polymorphism analysis showed that only one amplified fragment was different in the patient vs. control. Sequencing of the amplified fragments showed two missense point mutations, A698G and T788C, each of them mixed with the wild-type sequence. These mutations produced the changes H233R and L263P, leading to changes in the enzyme activity, which was largely abolished. The father and one brother of the proband were heterozygous for the L263P mutation and the mother and one daughter were heterozygous for the H233R mutation, which confirms the double-heterozygous character of the patient. Another sibling was free of the mutations. An enzymatic restriction analysis has been proposed to screen the occurrence of these two mutations in future patients.

Alleles↗

Type I glutaric aciduria: phenotypes and genotypes in 5 Taiwanese children.

We describe the clinical characteristics of 5 Taiwanese children with glutaric aciduria type I treated in a single medical center. Macrocephaly was present in 5 of these patients, psychomotor retardation in 4, and neurological regression in 2. Diagnosis was made prenatally in 1 patient due to an affected sibling. Low lysine/tryptophan formula, carnitine, and vitamin B2 were given to all patients. All patients disliked and could not adhere to the special formula and medications. Four older patients had neurological deficits prior to the start of the regimen. Among them, 1 died of sepsis and malnutrition. Only the prenatally diagnosed child did well at age 22 months. Mutational analysis, performed by polymerase chain reaction and sequencing, revealed an IVS10-2A>C defect in all 5 patients, and 2 siblings were homozygous. In addition, 2 novel mutations were detected. We conclude that GA I might not be as rare in Taiwan as previously thought. IVS10-2A>C is a common mutation in the Taiwanese population, whose genotypes are quite different from those of Caucasians.

Amino Acid Metabolism, Inborn Errors↗

A cobalamin metabolic defect with homocystinuria, methylmalonic aciduria and macrocytic anemia.

We have identified a patient with methylmalonic aciduria and homocystinuria due to a defect in cobalamin metabolism of the cb1C type mutant. At the time of admission at eight months of age the patient was malnourished, hypotonic and had macrocytic anemia. Neonatal screening for hypermethioninemia associated with homocystinuria had been normal. Serum vitamin B12 was markedly increased and folate concentration was above normal, as were urinary homocystine and methylmalonic acid. The patient had abnormal brain stem auditory and visual evoked potentials. Fibroblast activity of N5-methyltetrahydrofolate: homocysteine methyltransferase was reduced to approximately 10% of concurrent controls. A course of therapy with hydroxocobalamin resulted in a 90% reduction in excretion of methylmalonic acid and normalization of the evoked potentials. These studies support the efficacy of hydroxocobalamin therapy in this disease, suggest that methylmalonic acid may be the most appropriate metabolite to monitor for therapeutic response, and in importance of electrophysiologic studies in character in objectively monitoring the response to treatment metabolic disease.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗

Unveiling clinical and genetic landscapes of MMA and CBS: insights from whole exome sequencing in a tertiary care setting.

BACKGROUND: MMA and CBS deficiency are rare autosomal recessive metabolic disorders caused by defects in cobalamin metabolism and cystathionine-beta-synthase activity, respectively. Advanced molecular genetic techniques, have become essential for diagnosing these conditions. This study aimed to analyze the genetic variations in three MMA and four CBS deficiency cases using WES and correlate the findings with clinical, biochemical, and treatment outcomes. METHODS: Clinical evaluation, biochemical testing, neuroimaging, and WES were performed. WES data were analyzed using the reference genome GRCh37, and variants were classified according to ACMG guidelines. Treatment outcomes were monitored for three months post-intervention. RESULTS: In MMA cases, a homozygous pathogenic variant (c.394 C > T, p.Arg132Ter) in MMACHC was identified in all three patients. Biochemical abnormalities included methylmalonic aciduria, elevated homocysteine, and megaloblastic anemia. Hydroxycobalamin therapy improved behavioral, cognitive, and dermatological symptoms, though residual neuropathy persisted in one case. In CBS deficiency, pathogenic variants in CBS (c.992 C > T, p.Ala331Val; c.862 G > A, p.Ala288Thr; c.700 G > A, p.Asp234Asn) were identified. Clinical features included developmental delayed milestones, lens dislocation, and vascular complications. Treatment outcomes varied based on early diagnosis and compliance. CONCLUSION: This study highlights the importance of newborn screening program with WES in diagnosing and managing MMA and CBS deficiency, facilitating early intervention, improving clinical outcomes, and supporting precision medicine approaches. IMPACT: Early newborn screening and diagnosis are critical for effective treatment and improved patient outcomes. Novel clinical and pathogenic variants will expand the current understanding of these disorders. WES enhances the diagnostic precision for MMA and CBS deficiency, facilitating timely intervention and superior clinical management. Accurate and early detection of treatable IEMs through NBS can significantly reduce disease burden and healthcare costs.

Child, Preschool↗

Evidence of a single origin for the most frequent mutation (R402W) causing glutaryl-CoA dehydrogenase deficiency: identification of 3 novel polymorphisms and haplotype definition.

Glutaryl-CoA dehydrogenase (GCDH) deficiency causes glutaric aciduria type I (GA I), an inborn error of metabolism that is characterized clinically by dystonia and dyskinesia, biochemically by excretion of glutaric and 3-hydroxyglutaric acids in urine, and pathologically by neural degeneration of the caudate and putamen. To date, over 70 mutations in GCDH gene have been identified, single prevalent mutations have been found in communities in which GA I is particularly common, but generally GA I is heterogeneous. The most frequent mutation in Caucasians, R402W, has been identified in 12-16% of alleles. Here we report the frequency of mutation R402W in GA I Spanish patients, the characterization of three novel GCDH polymorphisms (IVS2+48T>C, IVS2-82T>G and 3'UTR 1518A>G) which, in combination with the two polymorphisms previously described (IVS2+64G>C, 1209G>T) gave rise to the first definition of GCDH haplotypes and their frequencies in control population. Linkage disequilibrium has been found between mutation R402W and a specific haplotype, suggesting a single origin for this mutation. Hum Mutat 15:207, 2000.

Amino Acid Substitution↗

Anorexia and altered serotonin metabolism in a patient with argininosuccinic aciduria.

We studied serotonin metabolism in a metabolically stable 7-year-old girl with argininosuccinic aciduria who had severe anorexia. The CSF concentration of 5-hydroxyindoleacetic acid (HIAA), the metabolite of serotonin, was markedly elevated at 79 ng/ml (normal 33 +/- 11 ng/ml). Altered serotonin metabolism was also reflected in the sleep EEG, which showed decreased REM sleep. Reducing her intake of tryptophan, the precursor of serotonin, from 35 mg/kg/day to 7 mg/kg/day resulted in a decrease in CSF concentration of HIAA to 20 ng/ml and the onset of spontaneous eating for the first time in 4 1/2 years. REM sleep increased from 3% to 9.5% of total sleep time. Two days after increasing tryptophan intake to 25 mg/kg/day, spontaneous feeding stopped, associated with a rise in CSF HIAA to 45 ng/ml. Caloric/carbohydrate intake was found to affect CSF HIAA levels and food intake in an additive manner with tryptophan intake. These observations suggest that altered serotonin metabolism affected feeding behavior in this child, and that this effect could be modified by changing tryptophan or carbohydrate intake.

Amino Acid Metabolism, Inborn Errors↗

Only one splice variant of the human TAZ gene encodes a functional protein with a role in cardiolipin metabolism.

Barth syndrome (BTHS) is an X-linked recessive disorder caused by mutations in the TAZ gene and is characterized by cardiomyopathy, short stature, neutropenia, and 3-methylglutaconic aciduria. Recently it was found that BTHS patients exhibit a profound cardiolipin deficiency although the biosynthetic capacity to synthesize this lipid from its precursor phosphatidylglycerol is entirely normal. Like BTHS patients, a Saccharomyces cerevisiae strain, in which the yeast orthologue of the human TAZ gene has been disrupted, exhibits an abnormal cardiolipin profile as determined by tandem mass spectrometry. Additionally, this yeast strain grows poorly on non-fermentable carbon sources. We have used both properties of this yeast disruptant as a read-out system to test the physiological functionality of each of 12 different splice variants that have been reported for the human TAZ gene. Our results demonstrate that only the splice variant lacking exon 5 was able to complement the retarded growth of the yeast disruptant on selective plates and restore the cardiolipin profile to the wild type pattern. We conclude that this splice variant most likely represents the only physiologically important mRNA, at least with regard to cardiolipin metabolism.

Acyltransferases↗