The following information may help to address your question:
What is short-chain acyl-CoA dehydrogenase (SCAD) deficiency?
Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is a rare genetic condition that prevents the body from converting certain fats (called short-chain fatty acids) into energy.
[1] This condition belongs to a group of disorders known as
fatty acid oxidation disorders (FOD).
[2] SCAD deficiency is caused by
mutations in the
ACADS gene.
[1] These mutations lead to a shortage (deficiency) of an
enzyme known as short-chain acyl-CoA dehydrogenase, which is involved in the breakdown of short-chain fatty acids. When not enough of this enzyme is present, excessive amounts of fatty acids and ammonia accumulate in the body.
[1][2] The symptoms of SCAD deficiency include a lack of energy, poor growth, and
developmental delay.
[1] Treatment for this condition typically includes a low-fat diet and avoidance of long periods without food (fasting).
[2]
Last updated: 2/5/2016
What symptoms may be associated with short-chain acyl-CoA dehydrogenase (SCAD) deficiency?
Some infants and children with SCAD deficiency may exhibit vomiting,
low blood sugar (
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 periods of fasting or during illnesses such as viral infections. In some cases, signs and symptoms may not appear until adulthood, when some individuals may develop muscle weakness and wasting. Some people are never diagnosed because they have very mild symptoms.
[1]
Last updated: 2/5/2016
What causes short-chain acyl-CoA dehydrogenase (SCAD) deficiency?
Mutations in the
ACADS gene cause SCAD deficiency. These mutations lead to inadequate levels of an
enzyme called short-chain acyl-CoA dehydrogenase. This enzyme is important for the breakdown of a particular type of fat called short-chain fatty acids. Reduced levels of this enzyme prevent short-chain fatty acids from being further broken down and processed in the
mitochondria (the energy-producing centers inside
cells). As a result, these short-chain fatty acids are not converted into energy, which can lead to the signs and symptoms of this disorder, such as lethargy, hypoglycemia, and muscle weakness.
[1]
Last updated: 2/5/2016
How do people inherit short-chain acyl-CoA dehydrogenase (SCAD) deficiency?
Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is
inherited in an
autosomal recessive pattern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.
[1]
Last updated: 2/5/2016
What is the risk that siblings or other members of our family will inherit short-chain acyl-CoA dehydrogenase (SCAD) deficiency?
When a genetic disorder is diagnosed in a family, family members often want to know the likelihood that they or their children will develop the condition. This can be difficult to predict in some cases because many factors influence a person’s chances of developing a genetic condition. One important factor is how the condition is inherited.
[3]
Two unaffected people who each carry one copy of the mutated gene for an autosomal recessive disorder (carriers) have a 25 percent chance with each pregnancy of having a child affected by the disorder. The chance with each pregnancy of having an unaffected child who is a carrier of the disorder is 50 percent, and the chance that a child will not have the disorder and will not be a carrier is 25 percent.[3]
To learn more about the specific risks to current or future members of your family, we recommend that seek the advice of a genetics professional. To learn more about what to expect from a genetics consultation, click here. Visit the Living With tab for Genetics Resources.
Last updated: 2/5/2016
How might short-chain acyl-CoA dehydrogenase (SCAD) deficiency be treated?
Treatment of short-chain acyl-CoA dehydrogenase (SCAD) deficiency usually consists of avoidance of fasting and a low fat diet. Supplemental carnitine may be recommended for some affected children during acute crises. Episodes of acute metabolic acidosis may be treated with intravenous hydration with a solution containing 10% glucose which can reestablish an anabolic state. This can be followed by reintroduction of the patient's usual diet.
[2]
Last updated: 2/5/2016
Can short-chain acyl-CoA dehydrogenase (SCAD) deficiency be treated through the use of replacement enzymes?
Although the treatment of beta-oxidation defects with the fatty acylglycerol triheptanoic acid is being investigated, enzyme therapy for short-chain acyl-CoA dehydrogenase (SCAD) deficiency is not currently available.
[4]
Last updated: 2/5/2016
We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please
contact us.
Warm regards,
GARD Information Specialist
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