3-Methylglutaconic aciduria: a new variant.

3-Methylglutaconic aciduria has been described in two distinct syndromes. In one there was deficient 3-methylglutaconyl coenzyme A hydratase in fibroblast extracts where the only clinical manifestation was retarded speech development. In the second syndrome, the enzyme activity was normal but prominent neurological deterioration was noted. We describe two siblings with 3-methylglutaconic aciduria with normal enzyme activity who had choreoathetoid movements, optic atrophy, and mild developmental delay. The boy demonstrated developmental improvement in his second year of life, and his sister developed well, with normal school performance. These patients represent a new clinical variant of the second syndrome with a relatively favorable prognosis.

Molecular basis of lipoamide dehydrogenase deficiency in Ashkenazi Jews.

We studied 13 patients with lipoamide dehydrogenase (LAD) deficiency, originating from seven Ashkenazi Jewish families. Their disease was characterized by recurrent attacks of vomiting, abdominal pain, and encephalopathy accompanied by elevated liver transaminases, prolonged prothrombin time, and occasionally associated with lactic and ketoacidemia or with myoglobinuria. Two patients who presented neonatally suffered from residual neurological damage with attention deficit hyperactive disorder, mild ataxia, motor incoordination, muscle hypotonia, and weakness. Nine patients who presented in early childhood or later suffered from exertional fatigue between decompensation episodes but were otherwise asymptomatic. Two patients died because of intractable metabolic acidosis and multi-organ failure. In all patients LAD activity was reduced to 8 to 21% of the control in muscle or lymphocytes. In four patients LAD protein in muscle was reduced to 20 to 60% of the control. Direct sequencing of the cDNA of the LAD gene showed that 12 of the 14 mutated alleles carried the G229C mutation and two carried an insertion mutation 105insA (Y35X). The patients who presented neonatally and had more severe sequelae were compound heterozygotes for the two mutations; patients who presented in early childhood or later were homozygous for the G229C mutation. Using an allele-specific oligonucleotide hybridization technique, nine heterozygotes for the G229C mutation were identified among 845 anonymous individuals of Ashkenazi Jewish origin disclosing a carrier rate of 1:94. Because of the significant morbidity associated with the disease, screening for the G229C mutation among Ashkenazi Jewish couples should be considered.

Antenatal presentation of carnitine palmitoyltransferase II deficiency.

Carnitine palmitoyl transferase (CPT) II deficiency is usually manifested around puberty by exercise induced myoglobinuria. Two Ashkenazi Jewish sibs with the rare antenatal form of CPTII deficiency are reported. On the 5th gestational month periventricular calcifications and markedly enlarged kidneys were found in both of them. The activity of CPTII in lymphocytes was undetectable and both sibs were homozygous for the 1237delAG mutation. Because of the serious consequences of homozygosity for this mutation, genotype determination of all Ashkenazi patients with the adolescent form of CPTII deficiency is warranted.

Behr's syndrome and 3-methylglutaconic aciduria.

We examined three patients from two families of Jewish-Iraqi origin who had progressive reduction of visual acuity and childhood onset of bilateral optic nerve atrophy without additional retinal abnormalities. They had neurologic symptoms compatible with Behr's syndrome. Neurologic signs included increased tendon reflexes, a positive Babinski sign, progressive spastic paraplegia, dysarthria, head nodding, and horizontal nystagmus. Neurologic involvement varied between affected siblings. The patients excreted excessive amounts of 3-methylglutaconic acid and 3-methylglutaric acid in their urine. We compared the characteristic ophthalmic features and the spectrum of neurologic signs encountered in this recently delineated autosomal recessive clinical entity with those of previously described entities associated with 3-methylglutaconic aciduria. Patients with early-onset optic atrophy should be examined for neurologic signs and screened for organic aciduria. A detailed ophthalmic examination is important in patients with neurologic abnormalities compatible with Behr's syndrome.

Striatal degeneration and spongy myelinopathy in glutaric acidemia.

The neuropathological findings in a 6 1/2-year-old boy with glutaric acidemia (GA) are described, and the pathology of 7 additional literature cases is briefly reviewed. Bilateral striatal degeneration and spongy change of the white matter were the salient features in this case and seem to represent the cardinal pathological features of the disease. Spongy myelinopathy was the result of intramyelinic vacuolation due to splitting of the myelin sheath along the intraperiod line, as illustrated here for the first time in GA. Based on morphological, biochemical and pharmacological data from humans and experimental animals, it is hypothesized that excitotoxin-mediated neuronal damage may account for the striatal degeneration, while toxic effect on myelin metabolism by the metabolic derangement of GA may explain the widespread white matter changes.

Lipoamide dehydrogenase activity in lymphocytes.

To assess the suitability of lymphocytes for patient diagnosis and carrier detection of lipoamide dehydrogenase deficiency, the activity of lipoamide dehydrogenase was determined in lymphocytes of six patients, seven obligate heterozygotes and 32 healthy controls. In healthy controls, lipoamide dehydrogenase activity was 80.7 +/- 23.6 nmol/min/mg protein, in obligate heterozygotes it was 36.0 +/- 12.1 nmol/min/mg protein and in the patients it was 13.3 +/- 5.1 nmol/min/mg protein. For the purpose of standardization, the results were also calculated as lipoamide dehydrogenase/citrate synthase activity ratio. The activity of lipoamide dehydrogenase and the lipoamide dehydrogenase/citrate synthase ratio differed significantly between the three groups (P < 0.005). We conclude that lymphocytes are suitable for the diagnosis of lipoamide dehydrogenase deficiency and for carrier detection.

A radiometric assay for aspartoacylase activity in human fibroblasts: application for the diagnosis of Canavan's disease.

A new sensitive method for measuring aspartoacylase activity in human skin fibroblasts using [3H]N-acetyl-L-aspartic acid (NAA) is described. Optimal assay conditions and kinetic parameters for enzyme activity were determined. The enzyme was found to have maximal activity at pH 8.5, and the Michaelis constant for the substrate N-acetylaspartate was 1.8-2.0 mmol/l. Aspartoacylase activity in control cultured human fibroblasts was 9.2 +/- 1.8 nmol/h per mg protein, compared with 1.1 +/- 0.2 in seven Canavan patients and 3.5 +/- 0.9 in four patients' parents. This method for determining aspartoacylase activity is advantageous to the previously described spectrophotometric method since it is rapid, more sensitive and has less nonspecific interference. It is possible that application of this technique to cultured ammniotic and chorionic villi cells may be used for prenatal diagnosis of Canavan's disease.

Cone and rod dysfunction in the NARP syndrome.

AIMS: Description of the ophthalmic manifestations of the NARP (neuropathy, ataxia, retinitis pigmentosa) syndrome that is associated with a point mutation in position 8993 of the mitochondrial DNA (mtDNA). METHODS: A mother and her two children, all carrying the 8993 mtDNA mutation, were examined. Two had manifestations of the NARP syndrome. A complete ocular and systemic examination was performed on all three patients. RESULTS: The clinical examination, electroretinogram, and visual fields revealed a typical cone-rod dystrophy in the son, and a typical cone dystrophy in the daughter. The mother had no ocular manifestations of the disease. CONCLUSIONS: NARP is a recently described, maternally inherited mitochondrial syndrome in which a retinal dystrophy, among other abnormalities, is related to a mutation of the mtDNA at nucleotide 8993. This study demonstrates the great variability of the ocular manifestations in the NARP syndrome. It also indicates that the retinal dystrophy in at least some NARP patients affects primarily the cones.

Complications following oat head aspiration.

We report 5 cases of oat head aspiration in children that resulted in serious complications due to the unidirectional migration of the oat head to the periphery of the lung. The complications included pneumothorax, pneumomediastinum, recurrent hemoptysis, chronic lung disease, bronchiectasis, lobectomy, bronchopleural and bronchocutaneous fistulae, pleural effusion, empyema cavity, and, one not described before, osteomylitis of the rib. Physicians should be aware of the dangers with this particular foreign body aspiration.

Holocarboxylase synthetase deficiency: a treatable metabolic disorder masquerading as cerebral palsy.

A 20-month-old boy of Jewish-Turkish origin presented with severe metabolic acidosis. He was born prematurely and had bacteremia during the neonatal period. Scaly skin eruption, developmental delay, generalized muscular hypertonia, and mild ventriculomegaly were noted during the 1st year. Holocarboxylase synthetase deficiency was diagnosed, and biotin and carnitine were administered. The skin rash and the organic aciduria resolved within several days, and at 30 months, his psychomotor development was appropriate for age. Metabolic evaluation should be performed in patients with combined neurologic and dermatologic symptoms even when medical history suggests a nonmetabolic etiology.

Ineffectiveness of oral coenzyme Q10 supplementation in 3-methylglutaconic aciduria, type 3.

Coenzyme Q10 was administered under placebo controlled blinded crossover conditions to six subjects suffering from type 3 3-methylglutaconic aciduria ('optic atrophy plus'), following a report of benefit. Despite attainment of high plasma levels of coenzyme Q10, no clinical benefit was observed and there was no diminution of urinary excretion of 3-methylglutaconic acid.

Muscular carnitine palmitoyltransferase II deficiency in infancy.

An 8-month-old female presented with febrile myoglobinuria. The activity of carnitine palmitoyltransferase (CPT) II was decreased to 16% of the control mean, and the oxidation of the long-chain fatty acids was reduced to 25% of the mean in the fibroblasts. Homozygosity for the common mutation, S113L, was identified in the CPT II gene. Residual CPT II activity of more than 10% of the mean and homozygosity for the common mutation S113L are usually associated with a milder reduction of long-chain fatty acid oxidation to about 80% of the control and with a later age of clinical onset. The early clinical presentation in the present patient is unique and was associated with a marked impairment of long-chain fatty acid oxidation, possibly because of other genetic factors. CPT II deficiency should be included in the differential diagnosis of isolated myoglobinuria in infancy.

Multiple syndromes of 3-methylglutaconic aciduria.

The most common clinical syndromes associated with 3-methylglutaconic aciduria are presented. In some patients these syndromes are multisystemic, progressive disorders of unknown etiology. Tissues deriving significant energy through oxidative metabolism (notably brain and cardiac muscle) are most often affected and in some the primary defect may reside within the mitochondrial respiratory chain. Although increasing biochemical evidence suggests that 3-methylglutaconic aciduria may correlate with deranged mitochondrial energy metabolism, the biochemical origin of 3-methylglutaconic acid and the significance of its increased excretion remain unknown. This review describes these syndromes and illustrates the necessity of urinary organic acid analysis to assist in the differential diagnosis.

The molecular background of glycogen metabolism disorders.

The molecular pathology of classical glycogen storage disorders, glycogen synthase deficiency and Fanconi-Bickel syndrome is reviewed. The isolation of the respective cDNAs, the chromosomal localization of the genes and the elucidation of the genomic organization enabled mutation analysis in most disorders. The findings have shed light on the multi-protein structure of the glucose-6-phosphatase system, the phosphorylase kinase enzymatic complex and the molecular background of the differential tissue expression in debranching enzyme deficiency. The immediate practical benefit of these studies is our extending ability to predict the outcome of clinical variants and to offer genetic counseling to most families. The elucidation of the tertiary structure of these proteins and their structure-function relationship poses major challenges for the future.

[Organic aciduria in Canavan disease].

3 male and 2 female infants with Canavan disease proven in some by brain biopsy, whose symptoms appeared within the first 4 months of life, are presented. Urinary organic acids were analyzed by gas chromatography/mass spectrometry. All excreted large amounts of N-acetylaspartic acid, probably secondary to decreased activity of its hydrolase. The pathogenetic mechanism is not well understood. Analysis of urinary organic acids can replace brain biopsy in the diagnosis of this condition, and the diagnosis can now be made prenatally.

The spectrum of mutations of the aspartoacylase gene in Canavan disease in non-Jewish patients.

Canavan disease is an infantile neurodegenerative disease that is caused by mutations in the gene encoding the enzyme aspartoacylase. It has mainly been reported in Jewish families. Genotyping of newly diagnosed patients is essential for the carrier identification and prenatal diagnosis. The sequence of the coding region was determined in 15 non-Jewish patients and 9 new mutations were identified: Y109X, P183H, V186F, M195R, P280L, P280S, A287T, 245insA, and a tentative missplicing mutation which leads to skipping of exon 5. The common pan-European mutation, A305E, was identified in 40% of the alleles and the overall detection rate was 93%.