Skip to Content
Newborn Screening Ontario
Screening Results

Medium Chain Acyl CoA Dehydrogenase Deficiency (MCADD)Download version for offline viewing or printing

At a Glance

Approximate Incidence in Ontario

1 in 10,000

Marker Measured


Screening can Prevent

Seizures, coma, sudden death


Avoid fasting, aggressive treatment of illness

  • Screening is Important
    • In Ontario, a heel prick is used to take a few drops of blood from each baby shortly after birth. The blood is tested for more than 25 treatable diseases, including MCADD.
    • A screen positive result means that more tests are needed to know whether or not a baby has MCADD. It does not mean that a baby has MCADD. Babies identified at a young age through screening can be treated early to help prevent health problems
  • What is MCADD?

    MCADD is a rare, inherited (genetic) disease.

    • Babies with MCADD have cannot make certain fats into energy, especially during long periods without food (fasting).
    • The baby’s body can run out of energy, and become very ill.
  • Screening Positive for MCADD
    • It is normal for parents and guardians to feel worried when their baby has a screen positive result. A ‘screen positive’ result does not mean that a baby has MCADD. It means that there is a chance that the baby may have MCADD.
    • Follow-up testing is important to find out whether the baby truly has MCADD.
    • The baby’s health care provider or a health care provider at a newborn screening Regional Treatment Centre will discuss the results with the baby’s family.
    • Follow-up testing is arranged as soon as possible and involves blood and urine tests. Sometimes a small skin sample is needed.
    • It can take a few days to weeks to find out if a baby truly has MCADD or not. This waiting period can be hard for families and it is natural for parents/guardians to feel worried when their baby has a screen positive result.
  • Possible Follow-up Test Results
    • Normal – the baby does not have MCADD.
    • Abnormal – the baby does have MCADD and will need treatment. The family will be supported by a team of caring specialists.
    • Inconclusive – more testing is required. The baby will continue to be followed closely by a specialist to ensure that he/she receives optimal care.
  • Signs and Symptoms

    Most babies with MCADD are appear normal at birth but they are at risk of a serious health condition called a metabolic crisis.

    A metabolic crisis is a life-threatening episode caused by low blood sugar and/or the build-up of harmful substances in the blood.

    Symptoms of a MCADD metabolic crisis include:

    • poor feeding
    • vomiting
    • excessive sleepiness
    • irritability
    • muscle spasms
    • enlarged liver

    If a metabolic crisis is not treated, breathing problems, seizures, coma, brain damage and sometimes death can occur.

    Between episodes of metabolic crisis, children with MCADD are usually healthy. Early treatment is effective at preventing metabolic crises and permanent damage such as problems with movement, speech and intellectual disability.

    Screening and treatment aim to prevent metabolic crises and allow children with MCADD to lead healthy lives.

  • Treatment

    Treatment is started as early as possible and is usually life long.

    Treatment involves:

    • Frequent feeding, especially when ill
      • To prevent a metabolic crisis, babies with MCADD must not go a long time without eating.
    • Aggressive treatment of illnesses
      • Children with MCADD may need to go to the hospital for minor illnesses like a cold or flu, and any time they stop eating.
    • A diet low in certain fats may be recommended.
    • Supplements such as carnitine may be prescribed. These help the baby’s body process fats.
    • A team, including a metabolic doctor and a dietitian, cares for babies with MCADD.
    • Babies with MCADD have their health and development checked regularly.
    • If signs of a metabolic crisis (above) are present, urgent medical care must be found.
  • Living with MCADD
    • Treatment is very effective at preventing metabolic crises.
    • With early treatment and careful monitoring most babies with MCADD will lead healthy lives with normal growth and intelligence.
    • As children get older, the risk of metabolic crisis decreases.