Transient multiple acyl-CoA dehydrogenation deficiency in a newborn female caused by maternal riboflavin deficiency.

A newborn female presented on the first day of life with clinical and biochemical findings consistent with multiple acyl-CoA dehydrogenase deficiency (MADD). Riboflavin supplementation corrected the biochemical abnormalities 24 h after commencing the vitamin. In vitro acylcarnitine profiling in intact fibroblasts both in normal and riboflavin depleted media showed normal oxidation of fatty acids excluding defects in electron transfer flavoprotein (ETF), or ETF ubiquinone oxidoreductase (ETF:QO), or a genetic abnormality in flavin metabolism. In addition, sequencing of the genes encoding ETF and ETF:QO in the proband did not reveal any pathogenic mutations. Determination of the maternal riboflavin status after delivery showed that the mother was riboflavin deficient. Repeat testing done two years after the infant's birth and while on a normal diet showed that the mother was persistently riboflavin deficient and showed a typical MADD profile on plasma acylcarnitine testing. A possible genetic defect in riboflavin transport of metabolism in the mother is postulated to be the cause of the transient MADD seen in the infant. Sequencing of the SLC16A12, RFK and FLAD1 genes encoding key enzymes in riboflavin transport of metabolism in the mother did not identify any pathogenic mutations. The underlying molecular basis of the mother's defect in riboflavin metabolism remains to be established.

Deficient muscle carnitine transport in primary carnitine deficiency.

Primary carnitine deficiency is associated with deficient blood and tissue carnitine concentrations. The clinical syndrome is dominated by heart and skeletal muscle symptoms, and the clinical response to oral carnitine supplementation is life-saving. Carnitine uptake has been shown to be defective in cultured skin fibroblasts and leukocytes obtained from patients with this condition. We report a new case of primary carnitine deficiency and offer direct evidence consistent with an impairment of carnitine uptake in differentiating muscle culture. The patient presented with severe and progressive cardiomyopathy and moderate proximal limb weakness. Plasma and muscle carnitine levels were very low, and the maximal rate of carnitine transport in cultured fibroblasts was deficient. An asymptomatic sister with intermediate levels of carnitine in plasma showed partially deficient carnitine uptake in fibroblasts, indicating heterozygosity. The patient's condition improved dramatically with oral carnitine therapy. Further studies were performed in cultured muscle cells at different stages of maturation, which demonstrated deficient maximal rates of carnitine uptake. Our findings are consistent with the concept that primary carnitine deficiency is the result of a generalized defect involving carnitine transport across tissue membranes.

Stridor as the major presenting symptom in riboflavin-responsive multiple acyl-CoA dehydrogenation deficiency.

UNLABELLED: Inspiratory stridor of unknown origin was the leading clinical symptom in an 11-month-old boy. The stridor increased over a period of 4 weeks, and assisted ventilation became necessary. Selective urinary screening by gas chromatography/mass spectrometry analysis revealed excretion of ethylmalonic and 3-OH-isovaleric acid and of N-isobutyryl-, N-2-methylbutyryl-, N-isovaleryl-, N-hexanoyl- and N-suberylglycine. Neither hypoglycaemia nor metabolic acidosis were noticed. Treatment with 200 mg of riboflavin per day led to a dramatic clinical improvement with restoration of normal respiration and an increase in muscular tone within 2 months. During this period, metabolite excretion in urine completely normalized. Riboflavin-sensitive multiple acyl-CoA dehydrogenation deficiency was confirmed in cultured fibroblasts. With riboflavin supplementation, the development of the child has been favourable, with normal school attendance now at an age of 9 years. CONCLUSION: As respiratory symptoms might precede other symptoms in disorders of mitochondrial oxidation, we propose determination of urinary organic acids in all cases of unexplained laryngeal stridor.

Multiple acyl-coenzyme A dehydrogenation disorder responsive to riboflavin: substrate oxidation, flavin metabolism, and flavoenzyme activities in fibroblasts.

Multiple acyl-CoA dehydrogenation disorders result from generalized defects in intramitochondrial acyl-CoA dehydrogenation. Fibroblasts from a riboflavin-responsive multiple acyl-CoA dehydrogenation disorder patient catabolized 14C-butyrate, -octanoate, and -leucine normally after culture in riboflavin-supplemented medium (2 mg/L). After culture in riboflavin-depleted medium (< or = 1.4 micrograms/L), his cells oxidized the same substrates poorly at 20 to 33% of control (p < 0.05). Patient cells incubated in a wide range of D-[2-14C]riboflavin concentrations (3, 31.4, and 100 micrograms/L) synthesized 14C-flavin mononucleotide and 14C-flavin adenine dinucleotide (FAD) normally and had normal cytosolic 14C-flavin mononucleotide and 14C-FAD contents, which argues against defects in cellular riboflavin uptake and conversion to flavin mononucleotide and FAD. After culture in 31.4 micrograms 14C-riboflavin/L for 2 wk, 14C-FAD specific radioactivities plateaued and were similar in patient and control cells. However, culturing these uniformly labeled cells in riboflavin-depleted medium for 2 wk lowered the patient's cellular 14C-FAD content to only 23% of control levels. Similarly, after incubation in low 14C-riboflavin concentrations (4.4 micrograms/L), the patient's mitochondrial 14C-FAD content was only 51% of control after 1 h and 29% of control at 4 h. After a 4-h incubation in a high physiologic concentration of 14C-riboflavin (31.4 micrograms/L), which raised the patient's cellular 14C-FAD levels 3- to 4-fold, his mitochondrial 14C-FAD content rose to normal; control values did not change. We also investigated possible defective FAD binding to flavoenzymes essential for acyl-CoA dehydrogenation.(ABSTRACT TRUNCATED AT 250 WORDS)

Glutaric acidemia type II. Heterogeneity in beta-oxidation flux, polypeptide synthesis, and complementary DNA mutations in the alpha subunit of electron transfer flavoprotein in eight patients.

We studied metabolic, polypeptide and genetic variation in eight glutaric acidemia type II (GA II) patients with electron transfer flavoprotein (ETF) deficiency. As measured by 3H-fatty acid oxidations in fibroblasts, beta-oxidation pathway flux correlated well with clinical phenotypes. In six patients with severe neonatal onset GA II, oxidation of [9,10(n)-3H]-palmitate ranged from 2% to 22% of control and of [9,10(n)-3H]myristate, from 2% to 26% of control. Of two patients with late onset GA II, one had intermediate residual activities with these substrates and the other normal activities. Radiolabeling and immunoprecipitation studies revealed that three of the six neonatal onset GA II patients had greatly diminished or absent alpha- and beta-ETF subunits, consistent with a failure to assemble a stable heterodimer. Another neonatal onset patient showed normal synthesis of beta-ETF but decreased synthesis of alpha-ETF. Two neonatal onset and two late onset GA II patients showed normal synthesis of both subunits. Analysis of the pre-alpha-ETF coding sequence revealed seven different mutations in the six patients with neonatal onset GA II. The most common mutation was a methionine for threonine substitution at codon 266 found in four unrelated patients, while all the other mutations were seen in single patients. No mutations were detected in the two patients with late onset GA II.

Abetalipoproteinemia. Report of an unusual patient.

Abetalipoproteinemia (Bassen-Kornzweig syndrome, acanthocytosis) was diagnosed at age 13 months in a black male. At age 13 months, the electroretinogram was nonrecordable and a pigmentary retinopathy was obvious with ophthalmoscopy. Following dietary modification and vitamin supplementation, the scotopic electroretinogram improved to about 30% of normal.

Effect of selenium compounds on selenium content, growth and 35S-cystine metabolism of skin fibroblasts from normal and cystinotic individuals.

Kidney samples from children with the inborn metabolic disease cystinosis contain 4 times more selenium (Se) than do kidney samples from normal individuals (p = 0.1). However, when cultured skin fibroblasts from cystinotic patients and normal control individuals are incubated in Se-D,L-methionine, Se-D,L-cystine, Se-cystamine X HCl, Se-urea, selenite or in medium without added selenium, only the cystinotic fibroblasts grown in Se-urea or selenite (SeO3=) contain more selenium than do the corresponding normal cells (p less than 0.05). In both types of cultured fibroblasts, the order of descending toxicity per ppm selenium is: Se-urea greater than Se-cystamine greater than Se-cystine greater than or equal to SeO3= much greater than Se-methionine. High (apparently toxic) concentrations of Se-urea and Se-cystamine lower the elevated intracellular free (nonprotein) cystine content of cystinotic fibroblasts to less than 60% of control values; at lower concentrations, these compounds raise the cystine content of these cells to over 140% of control values. Appropriate concentrations of SeO3=, Se-cystine and Se-methionine also elevate the free cystine content of the cystinotic cells. During a 75 minute incubation in 35S-cystine, the incorporation of 35S into the acid precipitable (protein) fraction of both cell types is significantly inhibited by Se-cystamine (approximately 55% control; p less than 0.05). The incorporation of 35S-cystine into glutathione is inhibited by Se-cystine (approximately 40% control) in both fibroblast types (p less than 0.05). In cystinotic cells, Se-cystamine significantly reduces incorporation of 35S-cystine into the cystine pool (40% control) as does SeO3= (67% control; p less than 0.05). Protein and glutathione synthesis in cystinotic fibroblasts are more strongly inhibited by Se-cystine and SeO3=, respectively, than in normal fibroblasts (p less than 0.05). These studies demonstrate that selenium compounds exhibit a different sequence of toxicity in fibroblasts than in the intact animal and that some previously unreported metabolic effects (i.e. inhibition of glutathione synthesis) may contribute to their toxicity.

Sudden infant death syndrome: plasma vitamin E levels and dietary factors.

Vitamin E and selenium deficiency have previously been suggested to be responsible for the Sudden Infant Death Syndrome (SIDS). New experimental data reveal that this is not the case since vitamin E as well as plasma selenium levels of SID infants are approximately equal to those of normal controls. Although breast feeding was believed to have a protective effect against SIDS, a statistical study of groups of SID- and control infants in San Diego County indicate no such correlation. Totally or partially breast-fed SID infants actually died at an earlier age than those fed by formula only (p=0.02). Compared to matched normal controls, SID infants appear to have received a less varied diet with a lower incidence of extradietary vitamin supplementation (p=0.02). There is also a somewhat greater prevalence of mothers smoking during pregnancy in the SID group (one-tail p=0.05).