Short chain acyl-CoA dehydrogenase deficiency (SCADD)
Deficiency of acyl-CoA dehydrogenase short chain (SCADD) is a rare congenital disorder of the oxidation of fatty acids into the mitochondria. It is inherited in an autosomal recessive manner.
SCADD is due to mutations in the gene ACADS (12q24.31) encoding short chain acyl-CoA dehydrogenase C2 to C3, as well as additional triggers still unknown.
SCADD has been defined as the presence of an increase in butirilcarnitina concentration (C4) in plasma, increased concentration of ethylmalonic acid (EMA) in urine, or both, in conditions of absence of stress (in at least twice), and mutations in homozygosis in the ACADS gene or variations associated with susceptibility: c.511C>T and c.625G>A.
The differential diagnosis includes multiple deficiency acyl-CoA dehydrogenase (MADD), the ethylmalonic encephalopathy and acute intoxication by consumption of ackee fruit.
Most patients are asymptomatic and do not require treatment. In affected individuals, the observed manifestations are convulsions, developmental delay (delay to sit and walk and to talk or maintain social interaction) and poor growth and poor nutrition as well as muscle weakness and hypotonia. These patients receive riboflavin, they are subjected to a diet low in fat and high in carbohydrates, and they are advised to avoid fasting. Acute metabolic acidosis can be treated with high concentrations of dextrose (with or without insulin) and intravenous fluids. Convulsions can be treated with anticonvulsants, but should avoid valproate. Pregnancies should be monitored to avoid complications such as acute fatty liver and preeclampsia. Monitoring in a medical centre specializing in metabolic disorders should include regular evaluation of growth, development and nutritional status of the patient.
The prognosis is good in asymptomatic patients, but variable in those with disease manifestations.