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Short-chain acyl-CoA dehydrogenase deficiency

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Also known as:
  • SCAD
  • SCADD deficiency
  • ACADS deficiency
  • lipid-storage myopathy secondary to short-chain acyl-CoA dehydrogenase deficiency
  • SCADH deficiency
  • short-chain acyl-coenzyme A dehydrogenase deficiency

Short-chain acyl-CoA dehydrogenase deficiency (SCAD) is a condition in which the body is unable to break down certain fats. SCAD is considered a fatty acid oxidation condition because people affected by the condition are unable to change some of the fats they eat into energy the body needs to function. Most individuals who are identified as having SCAD never experience symptoms, while some individuals experience serious health effects. Detecting the condition early and beginning treatment may help prevent many of the serious outcomes of SCAD.

Follow-Up Testing

Your baby’s doctor may ask you if your baby is showing any of the signs of SCAD (see Early Signs below). If your baby has certain signs, your baby’s doctor may suggest starting immediate treatment.

If your baby’s newborn screening result for short-chain acyl-CoA dehydrogenase deficiency (SCAD) was out of the normal range, your baby’s doctor or the state screening program will contact you to arrange for your child to have additional testing. It is important to remember that an out-of-range screening result does not necessarily mean that your child has the condition. An out-of-range result may occur because the initial blood sample was too small or the test was performed too early. However, as a few babies do have the condition, it is very important that you go to your follow-up appointment for a confirmatory test. Because the harmful effects of untreated SCAD can occur soon after birth, follow-up testing must be completed as soon as possible to determine whether or not your baby has the condition.

Follow-up testing will often involve testing urine, blood, or skin for signs of SCAD. Certain acids and toxins build up in the body when a child has a fatty acid oxidation condition, so measuring the amounts of these substances in your baby’s blood and urine can help doctors determine if your baby has a condition. High levels of C:4 acylcarnitines and ethylmalonic acid in the urine might indicate that your baby has SCAD.


About Short-chain acyl-CoA dehydrogenase deficiency

Early Signs

Each child with short-chain acyl-CoA dehydrogenase deficiency (SCAD) has a different experience. Your baby may show signs of SCAD, but some babies with SCAD never show any signs.

In babies, the signs of SCAD include:

    • Sleeping longer or more often
    • Behavior changes
    • Irritable mood
    • Poor appetite
    • Fever
    • Diarrhea
    • Vomiting
    • Trouble breathing
    • Seizures (Epilepsy)
    • Delayed growth and weight gain
    • Developmental delays
    • Hyperactivity
    • Weak muscle tone (known as hypotonia)
    • Small head size
    • Low blood sugar (called hypoglycemia)

Many of these signs may occur when your baby eats food that his or her body cannot break down. They can be triggered by long periods of time without eating, illnesses, and infections.

If your baby shows any of these signs, be sure to contact your baby’s doctor immediately.

Treatment
Dietary Treatment

Your baby may need to be on a restricted diet to avoid foods that contain fats that his or her body cannot break down. A dietician or nutritionist can help you plan a healthy diet for your baby.

Eating often can help avoid many of the signs mentioned in the Early Signs section.

Supplements and Medications

Some children with short chain acyl-CoA dehydrogenase deficiency (SCAD) take prescription L-carnitine supplements. L-carnitine is a substance naturally made by the body, but your baby’s body might not make enough of it. Taking L-carnitine supplements can help the body break down fats and get rid of harmful substances. Your baby’s doctor will need to write a prescription for these supplements.

Your doctor might also prescribe riboflavin (Vitamin B2) supplements.

Expected Outcomes

Children who are treated early for short-chain acyl-CoA dehydrogenase deficiency (SCAD) can have healthy growth and development. This is why newborn screening is so important.

With treatment, children may still develop learning delays, muscle weakness, or liver trouble.

It is currently unknown how effective treatments are in preventing signs of SCAD.

Causes

When we eat food, enzymes help break it down. Some enzymes break down fats into their building blocks, called fatty acids. Other enzymes break down these fatty acids. The enzyme short-chain acyl-CoA dehydrogenase helps break down fatty acids.

Fatty acids are built like chains and they come in a variety of lengths. They are categorized as either short, medium, long, or very long. Short-chain acyl-CoA dehydrogenase specializes at breaking down short length fatty acid chains for energy. If you have a question about what makes a “short” fatty acid, check out this link.

If your baby has short-chain acyl-CoA dehydrogenase deficiency (SCAD), his or her body does not make enough of this enzyme. When this happens, the body cannot break down short-chain fatty acids for energy.

Fatty acids are important sources of energy for the heart, especially when the body is low in sugar, such as between meals. When fatty acids cannot be broken down, harmful substances accumulate in the body. Acid levels rise in the blood, which can be dangerous. Everyone has some acid in his or her blood, but high levels can be toxic.

SCAD is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for SCAD, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with SCAD is rare, when both parents are carriers, they can have more than one child with the condition. Learn more about autosomal recessive inheritance.

 


Support for Short-chain acyl-CoA dehydrogenase deficiency

Support Services

Support groups can help connect families who have a child or other family member affected with SCAD with a supportive community of people who have experience and expertise in living with the condition. These organizations offer resources for affected individuals and their families, as well as health care providers.

Accessing Care

Work with your baby’s doctor to determine the next steps for your baby’s care. Your baby’s doctor may help you coordinate care with a doctor who specializes in metabolism, a dietician who can help plan your child’s specialized diet, and other medical resources in your community. Some children with SCAD have developmental delays. If you think that your baby is not meeting his or her developmental milestones, ask your baby’s doctor about the next steps in accessing a developmental evaluation and care.

Because SCAD is a genetic condition, you may want to talk with a genetics specialist. A genetic counselor or geneticist can help you understand the causes of the condition, discuss genetic testing for SCAD, and understand what this diagnosis means for other family members and future pregnancies. Speak with your baby’s doctor about getting a referral. The Clinic Services Search Engine offered by the National Coordinating Center for the Regional Genetic and Newborn Screening Service Collaboratives and the Find a Genetic Counselor tool on the National Society of Genetic Counselors (NSGC) website are two good resources for you or your baby's health care provider to use to identify local specialists.

Families' Experiences

Evan was diagnosed with SCAD through newborn screening shortly after birth. He is now a healthy toddler, and his mother is working to make sure that he has as healthy a childhood as possible. Read Evan’s story on the FOD Support Group website.


States Screening for Short-chain acyl-CoA dehydrogenase deficiency

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