Assembly defects of multiple respiratory chain complexes in a child with cardiac hypertrophy associated with a novel ACAD9 mutation.

Patients carrying Acyl-CoA dehydrogenase 9 (ACAD9) mutations reported to date mainly present with severe hypertrophic cardiomyopathy and isolated complex I (CI) dysfunction. Here we report a novel ACAD9 mutation in a young girl presenting with severe hypertrophic cardiomyopathy, isolated CI deficiency and interestingly multiple respiratory chain complexes assembly defects. We show that ACAD9 analysis has to be performed in first intention in patients presenting with cardiac hypertrophy even in the presence of multiple assembly defects.

Maximal fat oxidation rates in endurance trained and untrained women.

The aim of the present study was to examine the differences in fat oxidation between endurance trained (ET) and untrained (UT) women. Eight ET and nine UT women performed a progressive cycle ergometer test until exhaustion. The rate of fat oxidation was similar at low work rates (

A method for quantitative acylcarnitine profiling in human skin fibroblasts using unlabelled palmitic acid: diagnosis of fatty acid oxidation disorders and differentiation between biochemical phenotypes of MCAD deficiency.

Inherited disorders of fatty acid oxidation are a group of acute life-threatening but treatable disorders, clinically complicated by severe hypoketotic hypoglycemia precipitated by prolonged fasting. Among them, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is by far the most frequent disorder. Here we report a modified method for quantitative acylcarnitine profiling by electrospray ionisation-tandem mass spectrometry (ESI-MS-MS) in human skin fibroblasts using unlabelled palmitic acid as substrate. The reliability of this method was tested in cultured skin fibroblasts from previously diagnosed patients with specific carnitine cycle and fatty acid beta-oxidation defects. Furthermore, acylcarnitine profiling was investigated in fibroblasts and dried blood spots from patients with different variants of MCAD deficiency. ESI-MS-MS-based investigation of cultured skin fibroblasts from patients with disorders of fatty acid oxidation revealed a pathognomonic acylcarnitine profiling. In addition, this method delineated different variants of MCAD deficiency, i.e. mild and classical. The octanoylcarnitine (C8)-to-decanoylcarnitine (C10) and C8-to-acetylcarnitine (C2) ratios were the most specific markers to differentiate mild and classical forms of MCAD deficiency in fibroblasts. Similar results were obtained by quantitative acylcarnitine profiling in dried blood spots. In conclusion, this novel technique is a powerful tool for the investigation of fatty acid oxidation disorders under standardized conditions in fibroblasts.

Neonatal screening for medium-chain acyl-CoA dehydrogenase deficiency.

Neonatal screening for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency has not yet been introduced in the UK, primarily because of uncertainty about the natural history of the disorder and concerns about the specificity of the screening test. To obtain data on these issues, we did a retrospective study in which we analysed the concentrations of acylcarnitines in stored neonatal blood spots, and reviewed patients with high octanoylcarnitine concentrations at age 7-9 years. The high morbidity and mortality associated with the disorder, and the specificity of acylcarnitine analysis seen in our study support the introduction of screening for MCAD deficiency.

Prevalence of the 985A>G mutation in the medium-chain acyl-CoA dehydrogenase (MCAD) gene in Sweden.

The prevalence of the 985A>G mutation in the medium-chain acyl-CoA dehydrogenase gene was determined in the Swedish population. A heterozygote frequency of 1:127 was observed. Morbidity data indicate that most of the homozygotes with this mutation are not diagnosed and probably remain asymptomatic.

Molecular diagnosis of medium-chain acyl-CoA dehydrogenase deficiency by oligonucleotide ligation assay.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a recessively inherited defect in the mitochondrial beta-oxidation of fatty acids. A single nucleotide change, the A985 --> G transition, in the MCAD gene accounts for approximately 90% of all the disease-causing mutations in the patients. We have used PCR to amplify a segment of the human MCAD gene and typed the allelic sequence variation at base 985 by a colorimetric oligonucleotide ligation assay (OLA). PCR/OLA provides a technique that permits differentiation of the homozygotes, heterozygotes, and normals for the A985 --> G allele in the MCAD gene. Genotyping of 1908 random Finnish DNA samples by OLA identified 10 carriers of the mutant allele, but no homozygotes were found. The calculated carrier frequency for the A985 --> G mutation was 1:191 (95% confidence limits, 1:118-1:501), and the calculated frequency for the A985 --> G homozygotes was 1:147,000 (95% confidence limits, 1:56,000-1:1,004,000).

Rapid testing for the MCAD G583A mutation, by PCR-mediated site directed mutagenesis, in an Australian population of SIDS patients.

Medium Chain Acyl CoA Dehydrogenase (MCAD) deficiency is the most common genetic disorder of fatty acid metabolism and has been reported as a cause of sudden death in infants. We investigated the incidence of a rare MCAD mutation (G583A) in a large population of SIDS patients. A method utilising PCR mediated site directed mutagenesis and restriction enzyme digestion was devised to enable rapid and simple testing of large numbers of samples. The G583A mutation was not detected in 413 SIDS patients tested suggesting the mutation is not an important cause of sudden death in infants. The prevalence of this mutation in the general population was estimated to be between 0 and 0.89%.

Whole blood levels of dodecanoic acid, a routinely detectable forensic marker for a genetic disease often misdiagnosed as sudden infant death syndrome (SIDS): MCAD deficiency.

We investigated whether or not elevated whole blood dodecanoic acid concentration was due to a beta-oxidation defect in fatty acid metabolism previously reported. We prospectively analyzed blood from 55 consecutive sudden infant death syndrome (SIDS) cases for fatty acid concentrations by gas chromatograph. Three of 55 cases had elevated dodecanoic acid concentrations (> or = 18.4 mg/L). The three SIDS cases with elevated blood dodecanoic acid were confirmed to have medium chain acyl-CoA dehydrogenase (MCAD) deficiency by outside laboratories, indicating that elevated dodecanoic acid is highly specific and sensitive for predicting MCAD deficiency in SIDS victims. Dodecanoic acid was easily detected in routine toxicology for acid and neutral drugs done at autopsy. MCAD deficiency is an autosomal recessive genetic disease, carrying a 25% recurrence risk. Families should be notified that siblings, both presently living and yet to be born, should be screened for this deficiency because MCAD deficiency can be treated, and sudden, unexplained infant deaths of living and subsequent offspring can be prevented.

Improved PCR/NcoI method for the molecular diagnosis of medium chain acyl-CoA dehydrogenase deficiency using dried blood samples: two-stage amplification using two different sets of primers improves accuracy and sensitivity.

A 985A-->G transition is the single prevalent mutation representing 89% of all variant medium-chain acyl-CoA dehydrogenase (MCAD) alleles that causes MCAD deficiency. We and others previously devised a molecular method for the detection of the 985G allele that involves PCR coupled with NcoI digestion. The method has been widely used. However, when used for the analysis of dried blood samples, it sometimes produced ambiguous results with weak target bands in the presence of numerous artifact bands. An improved version of the method has been developed here, involving two stages of amplification using two different sets of primers. In the first stage, the entire exon-11 was amplified. A small aliquot (5 microliters) of the first PCR products were directly used as a template for the second PCR amplification. The second PCR is similar to the original method, but utilizes a pair of primers encompassing a smaller section within exon-11. The upstream primer incorporates a substitution at 981, so that a NcoI site involving 985G is introduced in the copies of the variant allele, as in the original PCR/NcoI method. The improved 2-stage method produces an intense target band with a very high sensitivity, yet devoid of artifacts, providing clean, unequivocal results.

Measurement of acyl-CoA dehydrogenase activity in cultured skin fibroblasts and blood platelets.

The measurement of acyl-CoA dehydrogenase activity is an essential part of the investigation of patients with suspected defects of fatty acid oxidation, and recently the organometallic oxidant ferricenium hexafluorophosphate has been introduced as an electron acceptor for these assays. However, we show that when medium-chain acyl-CoA dehydrogenase activity was measured in cultured skin fibroblasts and platelets from patients with proven defects of this enzyme, there was considerable residual enzyme activity when this electron acceptor was used. The ferricenium assay is not as specific as the anaerobic ETF-linked assay in the biochemical diagnosis of medium-chain acyl-CoA dehydrogenase deficiency in fibroblasts, and therefore is of limited clinical applicability in its present form.

Molecular survey of a prevalent mutation, 985A-to-G transition, and identification of five infrequent mutations in the medium-chain Acyl-CoA dehydrogenase (MCAD) gene in 55 patients with MCAD deficiency.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an inborn error of fatty-acid oxidation that is characterized by fasting intolerance and recurrent episodes of hypoglycemic coma which can be fatal. Its incidence is one of the highest among genetic metabolic disorders. Using a modified PCR and NcoI digestion method, we have surveyed 46 additional, unrelated MCAD-deficient patients for a prevalent mutation, an 985A-to-G transition (985A----G), that we previously identified in nine MCAD-deficient patients. Among the total of 55 studied, 44 were homozygous and 10 were heterozygous for the 985G allele, whereas one did not carry this mutant allele, indicating that the prevalence of the 985G allele is 89.1%. Furthermore, we identified five other types of mutation: one each in three of the compound heterozygotes and two in the single non-985G patient. An RFLP study of 12 985G-homozygotes showed that all 24 alleles fell into a single haplotype. A questionnaire regarding the ethnic and national origin of their patients was sent to all referring investigators. All 41 patients for whom this information was provided were Caucasians. Of 29 patients whose country of origin was specified, 19 and five were from the British Isles and Germany, respectively. These data suggest that 985A----G may have occurred in a single person in an ancient Germanic tribe.

Specific diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in dried blood spots by a polymerase chain reaction (PCR) assay detecting a point-mutation (G985) in the MCAD gene.

The discovery of a point-mutation, adenine-to-guanine, at position 985 in the gene coding for MCAD (G985), gave the basis for an easy and specific polymerase chain reaction test. We tested the specificity of such a PCR based assay and detected correctly G985 and A985 in sequence verified cDNA clones. We showed that the G985 mutation is present in genomic DNA from 48 of 50 patients with confirmed MCAD deficiency, originating from various European countries, Australia and the USA. On the basis of this high frequency of the G985 mutation among patients, we improved and optimized the assay with respect to reliability and convenience for routine diagnostic and screening purposes. As little as 2 microliters blood from filter-paper blood-spots (Guthrie spots) is sufficient for the test.

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.