Diagnosis of medium-chain acyl-CoA dehydrogenase deficiency in lymphocytes and liver by a gas chromatographic method: the effect of oral riboflavin supplementation.

The activity of medium-chain acyl-CoA dehydrogenase (MCAD) with octanoyl-CoA as a substrate was measured in human lymphocytes by a gas chromatographic technique. Phenazine methosulfate was used as the primary electron acceptor. After the addition of crotonase and subsequent hydrolysis, the reaction product 3-hydroxyoctanoic acid was quantitated by capillary gas-liquid chromatography of the trimethylsilyl derivatives. Control subjects had MCAD activities of 3.46 +/- 0.18 nmol/mg protein/min (n = 15). Five patients were investigated while receiving no therapy at all; MCAD activity ranged from 0.08 to 0.23 in four of them and was 0.65 in the fifth one. Subsequent to the long-term administration of 50-150 mg/d of riboflavin to MCAD-deficient patients (n = 11), these activities increased to an average of 0.41 in 10 patients and 2.22 in one. The activities in 15 obligate heterozygotes were 1.91 +/- 0.41 nmol/mg protein/min, thus enabling a clear distinction from controls. Neither heterozygotes nor a control responded to riboflavin. The method was also applicable to postmortem liver tissue. One patient, who had died suddenly and unexpectedly at the age of 19 mo, was correctly diagnosed as MCAD-deficient, whereas five additional children who died of the sudden infant death syndrome showed normal activities.

3-Hydroxydicarboxylic aciduria due to long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency associated with sudden neonatal death: protective effect of medium-chain triglyceride treatment.

Two siblings were found to be affected by long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, one of which died suddenly and unexpectedly on the 3rd day of life suffering from extreme hypoketotic hypoglycaemia. The younger sibling started to have feeding problems, lowered consciousness, and liver dysfunction at the age of 5 months. Her urine contained large amounts of C6-C14 3-hydroxydicarboxylic acids and conjugated 3-hydroxyoctanoic acid, as verified by gas chromatography/mass spectrometry. Plasma long-chain acylcarnitine was increased. A clue to the diagnosis was given by the results of a phenylpropionic acid loading test. This revealed small, but significant amounts of conjugated 3-hydroxyphenylpropionic acid (phenylhydracrylic acid) in the patient's urine. Subsequently, the activity of long-chain 3-hydroxyacyl-CoA dehydrogenase was found to be deficient in cultured skin fibroblasts. Based on the findings obtained by a medium-chain triglyceride load, a diet enriched in this type of fat was prescribed. On this regimen the patient started to thrive, signs of cardiomyopathy disappeared, and her liver function normalized.

Rapid diagnosis of 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency via enzyme activity measurements in leukocytes or platelets using a simple spectrophotometric method.

Patients with 3-hydroxy-3-methylglutaric aciduria due to a deficiency of 3-hydroxy-3-methylglutaryl Coenzyme A lyase usually present with a life-threatening crisis of hypoglycemia, metabolic acidosis and hyperammonemia. Diagnosis of this inborn error of leucine degradation is usually based upon gas-chromatographic analysis of organic acids in a patient's urine. In this paper we describe a simple spectrophotometric method allowing the activity of HMG-CoA lyase to be measured in leukocytes or platelets within a few hours, thus contributing to a rapid, unequivocal diagnosis and subsequent treatment. The validity of the method was established by demonstrating a deficient activity of HMG-CoA lyase in two patients with 3-hydroxy-3-methylglutaric aciduria. Furthermore, using this method, heterozygote detection can be done with great reliability.

Adenylosuccinase deficiency: an inborn error of purine nucleotide synthesis.

Clinical and biochemical data are presented on eight children with adenylosuccinase deficiency. This newly discovered inborn error of purine metabolism is characterized by an accumulation in body fluids of succinyladenosine (S-Ado) and succinylaminoimidazole carboxamide riboside (SAICA riboside), the dephosphorylated derivatives of the two substrates of adenylosuccinase. Six living children (three boys and three girls) and one deceased sibling displayed severe psychomotor retardation. Epilepsy was documented in five cases, autistic features in three, and growth retardation associated with muscular wasting in a brother and sister. In the cerebrospinal fluid, plasma and urine of these patients, the S-Ado/SAICA riboside ratio was between 1 and 2. In striking contrast, the eighth patient (a girl) was markedly less mentally retarded. Most noteworthy, the S-Ado/SAICA riboside ratio in her body fluids was around 5, suggesting that her milder psychomotor retardation was causally linked to this higher ratio. Adenylosuccinase deficiency was demonstrated in the liver of all seven living children, in the kidney of three patients in whom the enzymatic activity was measured, and in the muscle of three patients, including the two with muscular wasting. In fibroblasts of the six severely retarded patients, adenylosuccinase activity was reduced to approximately 40% of normal; in the patient with the higher S-Ado/SAICA riboside ratio, it reached only 6% of normal. The clinical heterogeneity of adenylosuccinase deficiency justifies systematic screening for the enzyme defect in unexplained neurological disease.

3-Methylglutaconic aciduria: a phenotype in which activity of 3-methylglutaconyl-coenzyme A hydratase is normal.

3-Methylglutaconic aciduria has been found in two distinct syndromes. In one there is deficient activity of 3-methylglutaconyl coenzyme A hydratase, and the only clinical manifestation observed has been retardation of speech development. In the other, which includes a majority of the patients studied, we document that the activity of this enzyme in fibroblast extracts is normal. The phenotype of this disorder is one of profound neurological impairment with retarded psychomotor development, hypotonicity and/or spasticity, convulsions or EEG abnormalities, and sensorineural changes in the eye and ear.

The cerebro-costo-mandibular syndrome: third report of familial occurrence.

Two male sibs with cerebro-costo-mandibular syndrome and spina bifida are described. The parents are physically and radiologically normal. A short review of the pertinent literature is given with special emphasis on the mode of inheritance.

Urinary excretion of deuterated metabolites in patients with tyrosinemia type I after oral loading with deuterated L-tyrosine.

1. The metabolic fate of orally given deuterated L-tyrosine, 50 mg/kg body weight, was investigated in seven patients with tyrosinemia type I in order to obtain evidence that the primary defect is at the level of fumarylacetoacetase. 2. The absence of fumarylacetoacetase could be proved in liver biopsy specimens obtained from four patients. 3. All patients excreted deuterated succinylacetoacetate and deuterated succinylacetone was detected in six out of seven. The total amount of these compounds was rather low; maximal 8.3% of the dose. The peak of the excretion occurred 3-6 h after loading, indicating an endogenous formation of the metabolites. 4. All patients excreted deuterated 4-hydroxyphenyl acids, probably reflecting secondary 4-hydroxyphenylpyruvate dioxygenase deficiency connected with liver damage. 5. No evidence for other secondary routes of tyrosine metabolism was found.

A case of formiminoglutamic aciduria. Clinical and biochemical studies.

We describe a boy who excreted massive amounts of formiminoglutamic acid and hydantoin-5-propionic acid in his urine. He was mildly mentally retarded and epileptic, whereas his twin-brother was completely normal. Loading with L-histidine enhanced the excretion of both metabolites. Treatment was attempted with high doses of folic acid and methionine, but both were without effect on the excretion levels.

Chromatographic determination and mass spectrometric identification of gamma-glutamylphenylalanine, a urinary constituent in phenylketonuria.

The occurrence of gamma-glutamylphenylalanine in the urine of patients with phenylketonuria could be demonstrated using chromatographic techniques and mass spectrometry. Concentrations ranged up to 35 mg/l. Only a weak correlation between the urinary excretion of this compound and phenylalanine was seen. The ages of the patients investigated ranged from 2 weeks to 18 years. The origin of the dipeptide is discussed.

Two sisters with isovaleric acidaemia, multiple attacks of ketoacidosis and normal development.

Two sisters with isovaleric acidaemia are described. Both had multiple attacks of acetonaemic vomiting, sometimes leading to subcoma. Despite this they showed a completely normal mental development. Biochemical studies, clinical follow-up and attempts at treatment are presented.

Computer analysis of the EEG as an aid in the evaluation of dietetic treatment in phenylketonuria.

The effect on the EEG of the reintroduction of phenylalanine in the diet of 6 patients with PKU on treatment was studied. Patients received daily loads of 100 or 150 mg L-phenylalanine/kg, equally divided over the meals, and computerized spectral EEG analysis was performed. The following EEG changes were seen: (1) occurrence of activity in the low frequency band (2--5 c/sec), (2) change of frequency of dominant rhythms; (3) change in the degree of synchrony between identical frequencies, occurring in different derivations. EEG changes increased quantitatively parallel to increasing blood phenylalanine and reversed after stopping the phenylalanine administration, suggesting that the EEG abnormalities are a measure for the degree of intoxication caused by phenylalanine or its metabolites. It is suggested that the EEG data may be useful deciding to terminate the diet in PKU.