Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is a condition that prevents the body from converting certain fats into energy, especially during periods without food (fasting).

Signs and symptoms of SCAD deficiency may appear during infancy or early childhood and can include vomiting, low blood glucose (hypoglycemia), a lack of energy (lethargy), poor feeding, and failure to gain weight and grow at the expected rate (failure to thrive). Other features of this disorder may include poor muscle tone (hypotonia), seizures, developmental delay, and a small head size (microcephaly).

The symptoms of SCAD deficiency may be triggered by fasting or illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe condition that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.

In some people with SCAD deficiency, signs and symptoms do not appear until adulthood. These individuals are more likely to have problems related to muscle weakness and wasting.

The severity of this condition varies widely, even among members of the same family. Some individuals are diagnosed with SCAD deficiency based on laboratory testing but never develop any symptoms of the condition.

This disorder is thought to affect approximately 1 in 35,000 to 50,000 newborns.

Mutations in the ACADS gene cause SCAD deficiency. This gene provides instructions for making an enzyme called short-chain acyl-CoA dehydrogenase, which is required to break down (metabolize) a group of fats called short-chain fatty acids. Fatty acids are a major source of energy for the heart and muscles. During periods of fasting, fatty acids are also an important energy source for the liver and other tissues.

Mutations in the ACADS gene lead to a shortage (deficiency) of the SCAD enzyme within cells. Without sufficient amounts of this enzyme, short-chain fatty acids are not metabolized properly. As a result, these fats are not converted into energy, which can lead to the signs and symptoms of this disorder, such as lethargy, hypoglycemia, and muscle weakness. It remains unclear why some people with SCAD deficiency never develop any symptoms.

Genetic Testing Information

• Genetic Testing Registry: Deficiency of butyryl-CoA dehydrogenase

Genetic and Rare Diseases Information Center

• Short chain acyl-CoA dehydrogenase deficiency

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Catalog of Genes and Diseases from OMIM

• ACYL-CoA DEHYDROGENASE, SHORT-CHAIN, DEFICIENCY OF; ACADSD

Scientific Articles on PubMed

• PubMed

• Gallant NM, Leydiker K, Tang H, Feuchtbaum L, Lorey F, Puckett R, Deignan JL, Neidich J, Dorrani N, Chang E, Barshop BA, Cederbaum SD, Abdenur JE, Wang RY. Biochemical, molecular, and clinical characteristics of children with short chain acyl-CoA dehydrogenase deficiency detected by newborn screening in California. Mol Genet Metab. 2012 May;106(1):55-61. doi: 10.1016/j.ymgme.2012.02.007. Epub 2012 Feb 9. Citation on PubMed
• Gregersen N, Andresen BS, Pedersen CB, Olsen RK, Corydon TJ, Bross P. Mitochondrial fatty acid oxidation defects--remaining challenges. J Inherit Metab Dis. 2008 Oct;31(5):643-57. doi: 10.1007/s10545-008-0990-y. Epub 2008 Oct 7. Citation on PubMed
• Jethva R, Bennett MJ, Vockley J. Short-chain acyl-coenzyme A dehydrogenase deficiency. Mol Genet Metab. 2008 Dec;95(4):195-200. doi: 10.1016/j.ymgme.2008.09.007. Epub 2008 Nov 5. Citation on PubMed or Free article on PubMed Central
• Koeberl DD, Young SP, Gregersen NS, Vockley J, Smith WE, Benjamin DK Jr, An Y, Weavil SD, Chaing SH, Bali D, McDonald MT, Kishnani PS, Chen YT, Millington DS. Rare disorders of metabolism with elevated butyryl- and isobutyryl-carnitine detected by tandem mass spectrometry newborn screening. Pediatr Res. 2003 Aug;54(2):219-23. doi: 10.1203/01.PDR.0000074972.36356.89. Epub 2003 May 7. Citation on PubMed
• Nagan N, Kruckeberg KE, Tauscher AL, Bailey KS, Rinaldo P, Matern D. The frequency of short-chain acyl-CoA dehydrogenase gene variants in the US population and correlation with the C(4)-acylcarnitine concentration in newborn blood spots. Mol Genet Metab. 2003 Apr;78(4):239-46. doi: 10.1016/s1096-7192(03)00034-9. Citation on PubMed
• Pedersen CB, 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 TJ, Andresen BS, 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. 2008 Aug;124(1):43-56. doi: 10.1007/s00439-008-0521-9. Epub 2008 Jun 4. Citation on PubMed
• Pena L, Angle B, Burton B, Charrow J. Follow-up of patients with short-chain acyl-CoA dehydrogenase and isobutyryl-CoA dehydrogenase deficiencies identified through newborn screening: one center's experience. Genet Med. 2012 Mar;14(3):342-7. doi: 10.1038/gim.2011.9. Epub 2012 Jan 5. Citation on PubMed
• van Maldegem BT, Kloosterman SF, Janssen WJ, Augustijn PB, van der Lee JH, Ijlst L, Waterham HR, Duran R, Wanders RJ, Wijburg FA. High prevalence of short-chain acyl-CoA dehydrogenase deficiency in the Netherlands, but no association with epilepsy of unknown origin in childhood. Neuropediatrics. 2011 Feb;42(1):13-7. doi: 10.1055/s-0031-1275342. Epub 2011 Apr 15. Citation on PubMed
• van Maldegem BT, Wanders RJ, Wijburg FA. Clinical aspects of short-chain acyl-CoA dehydrogenase deficiency. J Inherit Metab Dis. 2010 Oct;33(5):507-11. doi: 10.1007/s10545-010-9080-z. Epub 2010 Apr 29. Citation on PubMed or Free article on PubMed Central
• Waisbren SE, Levy HL, Noble M, Matern D, Gregersen N, Pasley K, Marsden D. Short-chain acyl-CoA dehydrogenase (SCAD) deficiency: an examination of the medical and neurodevelopmental characteristics of 14 cases identified through newborn screening or clinical symptoms. Mol Genet Metab. 2008 Sep-Oct;95(1-2):39-45. doi: 10.1016/j.ymgme.2008.06.002. Epub 2008 Aug 3. Citation on PubMed or Free article on PubMed Central