Molecular pathogenesis of a novel mutation, G108D, in short-chain acyl-CoA dehydrogenase identified in subjects with short-chain acyl-CoA dehydrogenase deficiency
Department of Pediatrics, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. Human Genetics
(Impact Factor: 4.82).
04/2010; 127(6):619-28. DOI: 10.1007/s00439-010-0822-7
Short-chain acyl-CoA dehydrogenase (SCAD) is a mitochondrial enzyme involved in the beta-oxidation of fatty acids. Genetic defect of SCAD was documented to cause clinical symptoms such as progressive psychomotor retardation, muscle hypotonia, and myopathy in early reports. However, clinical significance of SCAD deficiency (SCADD) has been getting ambiguous, for some variants in the ACADS gene, which encodes the SCAD protein, has turned out to be widely prevailed among general populations. Accordingly, the pathophysiology of SCADD has not been clarified thus far. The present report focuses on two suspected cases of SCADD detected through the screening of newborns by tandem mass spectrometry. In both subjects, compound heterozygous mutations in ACADS were detected. The mutated genes were expressed in a transient gene expression system, and the enzymatic activities of the obtained mutant SCAD proteins were measured. The activities of the mutant SCAD proteins were significantly lower than that of the wild-type enzyme, confirming the mechanism underlying the diagnosis of SCADD in both subjects. Moreover, the mutant SCAD proteins gave rise to mitochondrial fragmentation and autophagy, both of which were proportional to the decrease in SCAD activities. The association of autophagy with programmed cell death suggests that the mutant SCAD proteins are toxic to mitochondria and to the cells in which they are expressed. The expression of recombinant ACADS-encoded mutant proteins offers a technique to evaluate both the nature of the defective SCAD proteins and their toxicity. Moreover, our results provide insight into possible molecular pathophysiology of SCADD.
Available from: Tatsushige Fukunaga
- "The SIFT scores for these two ACADS substitutions were classified as damaging, with both substitutions conserved between species. It has been reported that ACADS- P55L decreases the enzyme activity of SCAD  . Although the final diagnoses in Case 14 and Case 5 were acute encephalopathy and respiratory infection, respectively, it cannot be denied that these substitutions could have potentially affected the enzyme activity to a greater or lesser extent. "
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ABSTRACT: The recent introduction of metabolic autopsy in the field of forensic science has made it possible to detect hidden inherited metabolic diseases. Since the next generation sequencing (NGS) has recently become available for use in postmortem examinations, we used NGS to perform metabolic autopsy in 15 sudden unexpected death in infancy cases. Diagnostic results revealed a case of carnitine palmitoyltransferase II deficiency and some cases of fatty acid oxidation-related gene variants. Metabolic autopsy performed with NGS is a useful method, especially when postmortem biochemical testing is not available.
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ABSTRACT: Short-chain acyl-coenzyme A dehydrogenase deficiency (SCADD) is an autosomal recessive disorder of mitochondrial fatty acid oxidation associated with mutations in the ACADS gene (Acyl-CoA Dehydrogenase, Short-chain, OMIM #606885). SCADD is a heterogeneous condition that has been associated with various clinical phenotypes ranging from fetal metabolic decompensation in infancy to asymptomatic individuals. Here, the first Korean neonate diagnosed with SCADD by biochemical and genetic findings is reported. The patient has remained asymptomatic by avoiding hypoglycemia. An increased concentration of butylcarnitine was detected on newborn screening. Subsequent urine organic acid analysis showed increased urinary excretion of ethylmalonic acid. To confirm the presence of the genetic abnormality, all the coding exons of the ACADS gene and flanking introns were amplified by the polymerase chain reaction (PCR). Sequence analysis of the ACADS gene revealed novel homozygous missence mutations, c. 1031A>G (p.E344G) in exon 9. In summary, the first Korean patient with confirmed SCADD by genetic analysis is reported with novel mutation.
Available from: Jae-Don Oh
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ABSTRACT: The acyl-CoA dehydrogenase, C-2 to C-3 short chain (ACADS) gene is known to be related with fat metabolism, especially coverts the fat to the energy sources in cattle. In human, the mutations in this gene cause SCAD deficiency, which is one of the fatty acid metabolism disorders. The ACADS gene is located on bovine chromosome 17. The objective of this study was to identify SNPs in Hanwoo ACADS gene and identify the relationships with economic traits. In this study, two SNPs, T1570G SNP in exon 2 and G13917A SNP in exon 4, were observed. Moreover, in the coding region, 2 missense mutations, T (Cys) G (Trp) mutation at 1570 bp and G (Arg) A (Gln) mutation at 13917 bp, were observed. These mutations were subjected to the PCR-RFLP for typing 198 Hanwoo animals. The observed genotype frequency for T1570G was 0.135 (TT), 0.860 (TG) and 0.005 (GG), respectively. Also, 0.900 (GG) and 0.100 (GA) were observed for the G13917A mutation. The association of these SNPs with four economic traits, CW (Carcass Weight), BF (Backfat Thickness), LMA (Longissimus Muscle Area), MS (Marbling Score), were also observed. The results indicated that no significant results were observed in all four traits (P>0.05). This might indicate that further studies are ultimately needed to use the SNPs in ACADS gene in lager populations for effectively used for the marker assisted selection.
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