Acyl-CoA dehydrogenase, short chain, deficiency of

A genetic disorder affecting fatty acid metabolism

Acyl-CoA dehydrogenase, short chain, deficiency of
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Synonyms	SCAD deficiency
Pronounce	N/A
Specialty	N/A
Symptoms	Muscle weakness, hypoglycemia, lethargy
Complications	N/A
Onset	Infancy or early childhood
Duration	N/A
Types	N/A
Causes	Mutations in the ACADS gene
Risks	N/A
Diagnosis	Genetic testing, newborn screening
Differential diagnosis	N/A
Prevention	N/A
Treatment	Dietary management, avoidance of fasting
Medication	N/A
Prognosis	Variable, often good with management
Frequency	N/A
Deaths	N/A

Acyl-CoA dehydrogenase, short chain, deficiency of (SCAD deficiency) is a rare genetic disorder that affects the body's ability to metabolize certain fatty acids. It is caused by mutations in the ACADS gene, which encodes the enzyme short-chain acyl-CoA dehydrogenase. This enzyme is crucial for the breakdown of short-chain fatty acids in the mitochondria, a process that is part of fatty acid oxidation.

Pathophysiology

The deficiency of short-chain acyl-CoA dehydrogenase leads to an accumulation of unmetabolized fatty acids and their derivatives, which can be toxic to cells. This accumulation primarily affects tissues with high energy demands, such as muscle and liver tissue. The inability to properly oxidize fatty acids can result in a range of symptoms, particularly during periods of fasting or illness when the body relies more heavily on fat metabolism for energy.

Genetics

SCAD deficiency is inherited in an autosomal recessive pattern, meaning that an affected individual must inherit two copies of the mutated ACADS gene, one from each parent. Carriers, who have only one copy of the mutation, typically do not show symptoms. The ACADS gene is located on chromosome 12, and various mutations have been identified that can lead to SCAD deficiency.

Clinical Presentation

Symptoms of SCAD deficiency can vary widely among individuals. Some may remain asymptomatic, while others may experience:

• Hypoglycemia
• Muscle weakness
• Lethargy
• Developmental delays
• Failure to thrive

Symptoms often present in infancy or early childhood, particularly during periods of fasting or illness.

Diagnosis

SCAD deficiency can be diagnosed through newborn screening programs that detect elevated levels of certain metabolites in the blood. Confirmatory testing involves genetic analysis to identify mutations in the ACADS gene. Additional tests may include:

• Plasma acylcarnitine profile
• Urine organic acid analysis

Management

Management of SCAD deficiency focuses on preventing metabolic crises by avoiding fasting and ensuring adequate caloric intake, particularly during illness. Dietary management may include:

• Frequent meals and snacks
• A diet low in fat and high in carbohydrates
• Supplementation with carnitine

Prognosis

The prognosis for individuals with SCAD deficiency is generally good, especially with early diagnosis and appropriate management. Many individuals remain asymptomatic or have mild symptoms that can be effectively managed with dietary interventions.

Also see

• Fatty acid metabolism disorders
• Medium-chain acyl-CoA dehydrogenase deficiency
• Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency
• Carnitine palmitoyltransferase I deficiency