MCAD deficiency


Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an inherited disorder that prevents your body from breaking down certain fats and converting them into energy. As a result, the level of sugar in your blood can drop dangerously low. MCAD deficiency is present from birth.

In the U.S., most states screen for MCAD deficiency at birth. If MCAD deficiency is diagnosed and treated early, the disorder can be managed through diet and lifestyle actions. In rare cases, the disorder is not diagnosed until adulthood. Left untreated, it can lead to seizures, breathing difficulties, coma and other serious health problems.


MCAD deficiency is an inherited disorder. Signs and symptoms typically first appear in babies and young children. The disorder can lead to early health problems, such as vomiting and lack of energy. With MCAD, a defect (mutation) in your genes changes the way your body breaks down some fats. Genetic testing can reveal whether you have these mutations.

You must inherit the affected genes from both of your parents. If you inherit only one affected gene, you won't develop MCAD deficiency. With one affected gene, you are a gene mutation carrier and can pass the mutation on to your children. But they wouldn't develop the condition unless they also inherited an affected gene from the other parent.

Signs and symptoms of the disorder are often triggered when an affected person goes too long without eating. Viral infections also can cause MCAD deficiency-related reactions.


The main goal of treatment for MCAD deficiency is to prevent problems from occurring. It's important to have regular meals and snacks and choose foods that are high in carbohydrates and low in fat.

Talk with your doctor about what to do if symptoms develop. Some experts recommend giving simple carbohydrates, such as glucose tablets or sweetened, non-diet beverages, by mouth. If the symptoms are more serious, an intravenous (IV) line may be needed.

Last Updated Nov 17, 2017

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