Instituto Valenciano de Microbiología

Masía El Romeral
Ctra. de Bétera a San Antonio Km. 0.3
46117 Bétera (Valencia)
Phone. 96 169 17 02
Fax 96 169 16 37
CIF B-96337217


AcylCoA short chain dehydrogenase deficiency of ..., (Short-chain acyl-CoA dehydrogenase deficiency -SCAD-) - Gen ACADS

Deficiency acyl-CoA dehydrogenase short chain (SCAD), also known as SCAD deficiency is a condition that prevents the body to convert certain fats in energy, especially during periods fasting. Signs and symptoms of the disease may appear during infancy or early childhood and can include vomiting, hypoglycemia, lethargy, poor diet and lack of weight gain and growth at the expected rate. Additional features may include hypotonia, seizures, developmental delay and microcephaly.

These symptoms can be triggered by fasting or by diseases such as viral infections. Sometimes this disease is confused with Reye syndrome. In some people affected, the signs and symptoms associated with the disease do not appear until adulthood. These individuals are more likely to have problems related to muscle weakness and atrophy. The severity of this disease varies widely, even among members of the same family. Some individuals with SCAD deficiency never develop any symptoms of the disease.

This process is due to mutations in the gene ACADS, located on the long arm of chromosome 12 (12q24.31). This gene encodes the enzyme acyl-CoA dehydrogenase short chain required to metabolize short-chain fatty acid. Fatty acids are an important source of energy for the heart and muscles. During periods of fasting, the fatty acids are also an important source of energy for the liver and other tissues.

They have identified more than 55 mutations in the gene responsible ACADS deficiency acyl-CoA dehydrogenase short chain. Almost all mutations change the amino acids in the SCAD enzyme. These mutations deficiency acyl-CoA dehydrogenase short chain inside cells. Without sufficient concentrations of this enzyme, short-chain fatty acid are not metabolized properly. As a result, these fats are converted into energy, which can lead to signs and symptoms of illness such as lethargy, hypoglycemia and muscular weakness. It is not clear why some people with SCAD deficiency have no symptoms. Further , two polymorphisms in the gene ACADS an amino acid change in the SCAD enzyme. Unlike other changes in the gene, these polymorphisms do not cause SCAD deficiency, but may increase the risk of developing it . One of these polymorphisms replaces the amino acid arginine by tryptophan at amino acid position 147 of the protein (or Arg147Trp R147W). The other polymorphism changes the amino acid glycine by serine at amino acid position 185 of the protein (or Gly185Ser G185S). Other genetic and environmental factors probably influence the risk of developing SCAD deficiency when a person carries any of these polymorphisms.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with deficiency of acyl-CoA dehydrogenase short chain (SCAD), by complete PCR amplification of exons ACADS gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).