Alternative titles; symbols
HGNC Approved Gene Symbol: ACADS
SNOMEDCT: 124166007, 787412002; ICD10CM: E71.312;
Cytogenetic location: 12q24.31 Genomic coordinates (GRCh38) : 12:120,725,826-120,740,008 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 12q24.31 | Acyl-CoA dehydrogenase, short-chain, deficiency of | 201470 | Autosomal recessive | 3 |
Naito et al. (1988, 1989) cloned and sequenced cDNAs encoding the precursor of human placental SCAD (EC 1.3.99.2). The encoded precursor is 412 amino acids long. The sequence includes a 24-amino acid leader peptide moiety. Like the other 4 enzymes belonging to the acyl-CoA dehydrogenase family of genes, SCAD is a tetrameric mitochondrial flavoprotein. It is synthesized as a 44-kD precursor, transported into mitochondria, and proteolytically processed to its 41-kD mature form. Comparison of SCAD and MCAD (607008) showed a high degree of homology, suggesting that these enzymes evolved from a common ancestral gene and belong to a gene family.
Corydon et al. (1997) determined that the human SCAD gene is approximately 13 kb long and contains 10 exons. Kelly and Wood (1996) showed that the Acads gene in the mouse is a compact, single-copy gene approximately 5,000 bp in size. The gene consists of 10 exons ranging in size from 57 to 703 bp, and 9 introns ranging in size from 80 bp to approximately 700 bp.
By fluorescence in situ hybridization, Corydon et al. (1997) mapped the SCAD gene to the distal part of chromosome 12 and concluded that it is a single-copy gene.
In rodents, the electroencephalogram (EEG) during paradoxical sleep and exploratory behavior is characterized by theta oscillations. Tafti et al. (2003) showed that a deficiency in short-chain acyl-CoA dehydrogenase in mice caused a marked slowing in the theta frequency during paradoxical sleep only. They found expression of the Acads gene in brain regions involved in theta generation, notably the hippocampus. Microarray analysis of gene expression in mice with mutations in Acads indicated overexpression of Glo1 (138750), the gene encoding glyoxalase-1, a gene involved in the detoxification of metabolic by-products. Administration of acetyl-L-carnitine (ALCAR) to mutant mice significantly recovered slow theta and Glo1 overexpression. Thus, an unappreciated metabolic pathway involving fatty acid beta-oxidation also regulates theta oscillations during sleep.
Corydon et al. (1997) investigated the evolutionary relationship between SCAD and 5 other members of the acyl-CoA dehydrogenase family by 2 independent approaches that gave similar phylogenetic trees.
Naito et al. (1989) studied the mutant SCAD enzyme and cultured fibroblasts from 3 patients with SCAD deficiency (201470). No difference was observed on Southern or Northern blot analysis, suggesting that the defects in these cell lines were caused by point mutations. In a patient with SCAD deficiency, Naito et al. (1989) identified compound heterozygosity for 2 mutations in the ACADS gene (136C-T; 606885.0001 and 319C-T; 606885.0002).
In a study of 10 patients with ethylmalonic aciduria and SCAD deficiency in fibroblasts, Corydon et al. (2001) found that most carried the 625G-A (606885.0007) and/or the 511C-T (606885.0006) variations in the SCAD gene, found in homozygous or in double heterozygous form in 14% of the general population, and developed clinically relevant SCAD deficiency. The authors recommended that patients with even mild ethylmalonic aciduria should be tested for these variations.
Tein et al. (2008) reported 10 children of Ashkenazi Jewish descent with variable phenotypic expression of SCAD deficiency. Three patients were homozygous for the 319C-T mutation, and 7 were compound heterozygous for the 319C-T mutation and the 625G-A disease susceptibility polymorphism. Common clinical features included hypotonia, developmental delay, speech delay, myopathy, lethargy, and feeding difficulties. The highest concentrations of ethylmalonic aciduria were found in those homozygous for the 319C-T mutation. Five presumably unaffected parents were also compound heterozygous for the 319C-T mutation and 625G-A, indicating that this allelic combination is compatible with a milder or asymptomatic phenotype.
Among 114 individuals with SCAD deficiency identified by abnormal biochemical profiles, Pedersen et al. (2008) identified 29 different variations in the ACADS gene. Functional expression studies in mouse liver mitochondria indicated that 21 of the mutant proteins showed severely decreased tetramer formation, while 7 showed a temperature-dependent production of tetramers with reduced amounts compared to the wildtype protein. Mutant SCAD proteins with decreased ability to form tetramers (defined as loss-of-function) tended to be retained in chaperone complexes longer than wildtype proteins, and ultimately appeared as mitochondrial aggregates (defined as gain-of-function); thus, these mutations could show either loss-of-function or gain-of-function effects. The clinical phenotypes in this patient cohort were highly variable, and there were no clear genotype/phenotype correlations. Pedersen et al. (2008) suggested that ACADS protein misfolding is necessary, but not sufficient, for expression of the disease.
Associations Pending Confirmation
Suhre et al. (2011) reported a comprehensive analysis of genotype-dependent metabolic phenotypes using a GWAS with nontargeted metabolomics. They identified 37 genetic loci associated with blood metabolite concentrations, of which 25 showed effect sizes that were unusually high for GWAS and accounted for 10 to 60% differences in metabolite levels per allele copy. These associations provided new functional insights for many disease-related associations that had been reported in previous studies, including those for cardiovascular and kidney disorders, type 2 diabetes, cancer, gout, venous thromboembolism, and Crohn disease. Suhre et al. (2011) identified an association between butyrylcarnitine/propionylcarnitine ratio and rs2066938 in the ACADS gene, with a p value of less than 4.4 x 10(-305).
In a patient with SCAD deficiency (201470), Naito et al. (1989, 1990) found evidence of compound heterozygosity. One chromosome carried a C-to-T transition in nucleotide 136 which altered arg46 to trp. See 606885.0002 for the mutation in the other allele. The cell line studied was from the patient reported by Naito et al. (1989).
In a patient with SCAD deficiency (201470), Naito et al. (1989, 1990) identified compound heterozygosity for 2 mutations in the ACADS gene: a 319C-T transition, resulting in an arg107-to-cys (R107C) substitution, and R46W (606885.0001).
Tein et al. (2008) reported 10 children of Ashkenazi Jewish descent with variable phenotypic expression of SCAD deficiency. Three patients were homozygous for the 319C-T mutation, and 7 were compound heterozygous for the 319C-T mutation and the 625G-A (606885.0007) disease susceptibility polymorphism. Common clinical features included hypotonia, developmental delay, speech delay, myopathy, lethargy, and feeding difficulties. The highest concentrations of ethylmalonic aciduria were found in those homozygous for the 319C-T mutation. Five of the presumably unaffected parents were also compound heterozygous for the 319C-T mutation and 625G-A, indicating that this allelic combination is compatible with a milder or asymptomatic phenotype. In vitro functional expression studies showed that the 319C-T mutant protein was unable to form a functional tetramer, resulting in complete loss of enzyme activity. The carrier frequency of 319C-T was estimated to be 1 in 15 among Ashkenazi Jewish individuals, consistent with a founder effect.
Gregersen et al. (1998) characterized 3 disease-causing mutations (confirmed by lack of enzyme activity after expression in COS-7 cells) in 2 patients with SCAD deficiency (201470). One patient was a compound heterozygote for 2 mutations, 274G-T and 529T-C, resulting in gly68-to-cys and trp153-to-arg amino acid substitutions, respectively.
See 606885.0003 and Gregersen et al. (1998).
In a patient with SCAD deficiency (201470), Gregersen et al. (1998) found compound heterozygosity for a 511C-T point mutation in 1 allele (resulting in an arg147-to-trp amino acid substitution) and, in the other allele, an 1147C-T mutation (resulting in an arg359-to-cys amino acid substitution) together with the 625G-A polymorphism that is found in homozygous form in 7% of control individuals and in 60% of 135 patients with elevated urinary excretion of ethylmalonic acid (EMA). The 1147C-T mutation was not present in 98 normal alleles, but was detected in 3 alleles of 133 patients with elevated EMA excretion, consistently as a 625A-1147T allele.
In a girl with SCAD deficiency and low average IQ, Corydon et al. (2001) found heterozygosity for the 1147C-T change as well as homozygosity for the 625G-A variation (606885.0007).
Gregersen et al. (1998) found a 511C-T mutation in the SCAD gene, resulting in an arg147-to-trp (R147W) amino acid substitution, in 13 of 130 and 15 of 67 625G polymorphic alleles, respectively, of normal controls and patients with elevated EMA excretion; they never found it in association with the 625A variant. This overrepresentation of the haplotype 511T-625G among the common 625G alleles in patients compared with controls was significant (P less than 0.02), suggesting that the allele 511T-625G, like 511C-625A, confers susceptibility to ethylmalonic aciduria. Gregersen et al. (1998) concluded that ethylmalonic aciduria, a commonly detected biochemical phenotype, is a complex multifactorial/polygenic condition where, in addition to the role of SCAD susceptibility alleles, other genetic and environmental factors are involved.
Corydon et al. (2001) performed expression studies of the SCAD protein with the 511C-T change and found that R147W protein has 69% of wildtype activity.
Corydon et al. (2001) studied 10 patients with ethylmalonic aciduria and SCAD deficiency (201470) in fibroblasts and found a 625G-A change in the SCAD gene, resulting in a gly185-to-ser (G185S) substitution, in 9 of the patients, 5 of whom were homozygous for this variation (3 had additional mutations). One patient with dysmorphic features and developmental delay was heterozygous for this mutation and for 511C-T (606885.0006), both of which have been referred to as 'variations,' because 14% of the general population has been found to be either homozygous or double heterozygous for them. Expression studies in E. coli showed that the G185S SCAD protein has 86% of wildtype activity.
In a girl with SCAD deficiency (201470) who was noted in the neonatal period to have hypotonia and respiratory distress, Corydon et al. (2001) identified heterozygosity for a 268G-A change in the SCAD gene, resulting in a gly66-to-ser (G66S) substitution, in addition to homozygosity for the 625A variation (606885.0007). Expression studies of the G66S protein in E. coli showed undetectable SCAD activity.
In a boy with SCAD deficiency (201470) who was noted in the neonatal period to have hypotonia and later developmental delay, Corydon et al. (2001) identified a heterozygous 3-bp deletion (310-312delGAG) in the SCAD gene, resulting in the deletion of a glutamic acid residue at amino acid 80. Expression studies in E. coli for this allele showed undetectable activity. The patient was also heterozygous for the 625A allele (606885.0007).
In a boy with SCAD deficiency (201470) who presented in the neonatal period with hypotonia and seizures, Corydon et al. (2001) identified a heterozygous 575C-T change in the SCAD gene, resulting in an ala168-to-val (A168V) substitution. The patient was also heterozygous for a 973C-T change, resulting in an arg301-to-trp substitution (606885.0011), and homozygous for the 625A variation (606885.0007). Expression studies in E. coli revealed undetectable SCAD activity for the A168V mutant protein.
See 606885.0010 and Corydon et al. (2001). Expression studies in E. coli by Corydon et al. (2001) revealed undetectable SCAD activity for the arg301-to-trp mutant protein.
In a male infant with SCAD deficiency (201470) who presented at 3 months of age with hypotonia and developmental delay, Corydon et al. (2001) identified a heterozygous 1058C-T change in the SCAD gene, resulting in a ser329-to-leu (S329L) substitution. Expression studies in E. coli revealed undetectable SCAD activity for this mutant protein. The patient was also found to be heterozygous for the 625A variation (606885.0007).
In a girl with SCAD deficiency (201470) who presented in the neonatal period with hypotonia and seizures, Corydon et al. (2001) identified heterozygosity for a 1138C-T change in the SCAD gene, resulting in an arg356-to-trp (R359W) substitution. Expression studies in E. coli revealed undetectable SCAD activity for this mutant protein. The patient was also found to be heterozygous for the 625A variation (606885.0007).
In 2 unrelated Japanese girls with biochemical evidence of SCAD deficiency (201470) but without clinical manifestations, Shirao et al. (2010) identified compound heterozygosity for mutations in the ACADS gene. Both girls carried a 164C-T transition in exon 2, resulting in a pro55-to-leu (P55L) substitution, and 1 girl had a 1031A-G transition in exon 9, resulting in a glu344-to-gly (E344G; 606885.0015) substitution, and the other girl had a 323G-A transition in exon 3, resulting in a gly108-to-asp (G108D; 606880.0016) substitution. In vitro functional expression studies in HEK293 and human osteosarcoma cells showed that each of the 3 mutant proteins had less than 10% residual enzyme activity, were retained in the insoluble fraction of the cell consistent with abnormal aggregation, and caused increased mitochondrial fragmentation associated with autophagy. Despite the functional evidence of mutant ACADS dysfunction, neither girl showed symptoms at age 4 years; Shirao et al. (2010) noted that the genotype/phenotype correlation was unclear.
See 606885.0014 and Shirao et al. (2010).
See 606885.0014 and Shirao et al. (2010).
Corydon, M. J., Andresen, B. S., Bross, P., Kjeldsen, M., Andreasen, P. H., Eiberg, H., Kolvraa, S., Gregersen, N. Structural organization of the human short-chain acyl-CoA dehydrogenase gene. Mammalian Genome 8: 922-926, 1997. [PubMed: 9383286] [Full Text: https://doi.org/10.1007/s003359900612]
Corydon, M. J., Vockley, J., Rinaldo, P., Rhead, W. J., Kjeldsen, M., Winter, V., Riggs, C., Babovic-Vuksanovic, D., Smeitink, J., De Jong, J., Levy, H., Sewell, A. C., Roe, C., Matern, D., Dasouki, M., Gregersen, N. Role of common gene variations in the molecular pathogenesis of short-chain acyl-CoA dehydrogenase deficiency. Pediat. Res. 49: 18-23, 2001. [PubMed: 11134486] [Full Text: https://doi.org/10.1203/00006450-200101000-00008]
Gregersen, N., Winter, V. S., Corydon, M. J., Corydon, T. J., Rinaldo, P., Ribes, A., Martinez, G., Bennett, M. J., Vianey-Saban, C., Bhala, A., Hale, D. E., Lehnert, W., Kmoch, S., Roig, M., Riudor, E., Eiberg, H., Andresen, B. S., Bross, P., Bolund, L. A., Kolvraa, S. Identification of four new mutations in the short-chain acyl-CoA dehydrogenase (SCAD) gene in two patients: one of the variant alleles, 511C-T, is present at an unexpectedly high frequency in the general population, as was the case for 625G-A, together conferring susceptibility to ethylmalonic aciduria. Hum. Molec. Genet. 7: 619-627, 1998. [PubMed: 9499414] [Full Text: https://doi.org/10.1093/hmg/7.4.619]
Kelly, C. L., Wood, P. A. Cloning and characterization of the mouse short-chain acyl-CoA dehydrogenase gene. Mammalian Genome 7: 262-264, 1996. [PubMed: 8661694] [Full Text: https://doi.org/10.1007/s003359900078]
Naito, E., Indo, Y., Tanaka, K. Identification of two variant short chain acyl-coenzyme A dehydrogenase alleles, each containing a different point mutation in a patient with short chain acyl-coenzyme A dehydrogenase deficiency. J. Clin. Invest. 85: 1575-1582, 1990. [PubMed: 1692038] [Full Text: https://doi.org/10.1172/JCI114607]
Naito, E., Indo, Y., Tanaka, K. Short chain acyl-coenzyme A dehydrogenase (SCAD) deficiency: immunochemical demonstration of molecular heterogeneity due to variant SCAD with differing stability. J. Clin. Invest. 84: 1671-1674, 1989. [PubMed: 2808706] [Full Text: https://doi.org/10.1172/JCI114346]
Naito, E., Indo, Y., Tanaka, K. Short chain acyl-CoA dehydrogenase (SCAD) deficiency: demonstration of molecular heterogeneity and identification of point mutations. (Abstract) Am. J. Hum. Genet. 45 (suppl.): A208, 1989.
Naito, E., Ozasa, H., Ikeda, Y., Tanaka, K. Molecular cloning and nucleotide sequence of complementary DNAs encoding human short chain acyl-coenzyme A dehydrogenase and the study of the molecular basis of human short chain acyl-coenzyme A dehydrogenase deficiency. J. Clin. Invest. 83: 1605-1613, 1989. [PubMed: 2565344] [Full Text: https://doi.org/10.1172/JCI114058]
Naito, E., Ozasa, H., Ikeda, Y., Tanaka, K. Molecular cloning and nucleotide sequence of cDNA encoding human short chain acyl-CoA dehydrogenase (SCAD) and a study of its genetic deficiency. (Abstract) Am. J. Hum. Genet. 43: A197, 1988.
Pedersen, C. B., Kolvraa, S., Kolvraa, A., Stenbroen, V., Kjeldsen, M., Ensenauer, R., Tein, I., Matern, D., Rinaldo, P., Vianey-Saban, C., Ribes, A., Lehnert, W., Christensen, E., Corydon, T. J., Andresen, B. S., Vang, S., Bolund, L., Vockley, J., Bross, P., Gregersen, N. The ACADS gene variation spectrum in 114 patients with short-chain acyl-CoA dehydrogenase (SCAD) deficiency is dominated by missense variations leading to protein misfolding at the cellular level. Hum. Genet. 124: 43-56, 2008. [PubMed: 18523805] [Full Text: https://doi.org/10.1007/s00439-008-0521-9]
Shirao, K., Okada, S., Tajima, G., Tsumura, M., Hara, K., Yasunaga, S., Ohtsubo, M., Hata, I., Sakura, N., Shigematsu, Y., Takihara, Y., Kobayashi, M. Molecular pathogenesis of a novel mutation, G108D, in short-chain acyl-CoA dehydrogenase identified in subjects with short-chain acyl-CoA dehydrogenase deficiency. Hum. Genet. 127: 619-628, 2010. [PubMed: 20376488] [Full Text: https://doi.org/10.1007/s00439-010-0822-7]
Suhre, K., Shin, S.-Y., Petersen, A.-K., Mohney, R. P., Meredith, D., Wagele, B., Altmaier, E., CARDIoGRAM, Deloukas, P., Erdmann, J., Grundberg, E., Hammond, C. J., and 22 others. Human metabolic individuality in biomedical and pharmaceutical research. Nature 477: 54-60, 2011. [PubMed: 21886157] [Full Text: https://doi.org/10.1038/nature10354]
Tafti, M., Petit, B., Chollet, D., Neidhart, E., de Bilbao, F., Kiss, J. Z., Wood, P. A., Franken, P. Deficiency in short-chain fatty acid beta-oxidation affects theta oscillations during sleep. Nature Genet. 34: 320-325, 2003. [PubMed: 12796782] [Full Text: https://doi.org/10.1038/ng1174]
Tein, I., Elpeleg, O., Ben-Zeev, B., Korman, S. H., Lossos, A., Lev, D., Lerman-Sagie, T., Leshinsky-Silver, E., Vockley, J., Berry, G. T., Lamhonwah, A.-M., Matern, D., Roe, C. R., Gregersen, N. Short-chain acyl-CoA dehydrogenase gene mutation (c.319C-T) presents with clinical heterogeneity and is candidate founder mutation in individuals of Ashkenazi Jewish origin. Molec. Genet. Metab. 93: 179-189, 2008. [PubMed: 18054510] [Full Text: https://doi.org/10.1016/j.ymgme.2007.09.021]