Medium-chain acyl-CoA dehydrogenase deficiency

What is medium-chain acyl-coa dehydrogenase deficiency

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an inherited (genetic) condition that prevents the body from breaking down certain fats and turning them into energy.

MCAD is an enzyme that processes a type of fat called medium-chain fatty acids. This enzyme helps break down these fatty acids so your body can use or get rid of them.

Without enough of this enzyme, the body has trouble using fats for energy. This condition can be more or less severe depending on how much of the enzyme your baby can make.

Breaking down fat for energy allows your body to work properly, and it is especially important after a long time without food (fasting) and during illness. If your body does not make enough energy from fat, blood sugar levels can become dangerously low.

If untreated, the lack of energy leads to the signs and symptoms of the condition. In severe cases, this condition can result in brain damage, coma, or death if not treated early.

Newborn Screening and Follow-Up

Screening for medium-chain acyl-coa dehydrogenase deficiency

Newborn screening for MCAD deficiency is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.

During screening, a special machine measures how much of certain substances (called acylcarnitines) are in your baby’s blood. Your body produces these substances when it makes energy from fats. Babies with high levels of these substances might have MCAD deficiency.

What Happens After an Out-of-Range Screening Result?

If your baby’s blood spot screening result for MCAD deficiency is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.

An out-of-range screening result does not mean that your baby definitely has the condition. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.

Your baby may need the following tests after an out-of-range screening result:

• Blood and/or urine tests
• Genetic testing using a blood sample

You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems soon after birth if they are not diagnosed and treated quickly.

False-positive newborn screening results for this condition are rare. However, certain medications, like carnitine supplements or some seizure medications (valproate), may affect the results of screening.

Condition Details

Signs and Symptoms

Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.

Signs of MCAD deficiency often appear anywhere from shortly after birth to 2 years of age. Common illnesses like a cold or flu can trigger symptoms. Babies can also have life-threatening signs of MCAD when they are not getting enough calories from breastmilk or are going too long between feedings.

Signs of the condition may include the following:

• Weakness
• Tiredness or lack of energy (lethargy)
• Breathing problems
• Vomiting
• Seizures
• Low blood sugar (hypoglycemia)

Cause

The condition is caused by a change in the ACADM gene. This gene gives the body instructions for making MCAD. MCAD is an enzyme that breaks down a certain type of fat, called medium-chain fatty acids. This type of fat is an important source of energy for the heart, liver, and muscles.

Without a working ACADM gene, your baby cannot make enough MCAD enzyme. As a result, they cannot properly break down fat to make energy and get rid of toxins.

Inheritance and Family Concerns

MCAD deficiency is a genetic condition. Babies inherit it from their biological (birth) parents. To learn more about genetic conditions, visit MedlinePlus Genetics.

• MCAD deficiency is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking ACADM gene to their baby. Only babies with two nonworking ACADM genes—one from the mom and one from the dad—have this condition.
  • People with one working copy and one nonworking copy of the ACADM gene are called carriers.
  • Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
  • If two parents are carriers of a nonworking copy of the ACADM gene, they have a 1 in 4 chance of having a child with MCAD deficiency.
  • Carriers for MCAD deficiency often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with MCAD deficiency.
  • Parents who already have a child with MCAD deficiency still have a 1 in 4 chance of having another child with MCAD deficiency. This 1 in 4 chance stays the same for all future children.

  Treatment and Management

  It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.

  Treatments may include the following:

  • Regular and frequent meals and snacks
  • Diet high in carbohydrates and low in fat
  • L-carnitine supplements to help the body break down fats
  • People with MCAD deficiency must be very careful if they get sick and have vomiting or diarrhea, or do not want to eat. They may need emergency care to prevent low blood sugar levels.

  Children who receive early and continuing treatment for MCAD deficiency can have healthy growth and development.

  Related Resources

  Resources For This Condition

  • FOD Family Support Group
  • MedlinePlus Genetics
  • National Organization for Rare Disorders
  • Minutes Matter

  Additional Resources

  For a listing of general support, advocacy, and informational resources for Newborn Screening, visit the Resources page.