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California Newborn Screening Program

Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)

What is MCADD?

MCADD stands for "medium chain acyl-CoA dehydrogenase deficiency". It is one type of fatty acid oxidation disorder. People with this type of disorder have problems breaking down fat into energy for the body. The enzyme "medium chain acyl-CoA dehydrogenase" is either missing or not working properly.  This enzyme’s job is to break down certain fats in the food we eat into energy. It also breaks down fat already stored in the body. When the enzyme is missing or not working, the body cannot use fat for energy, and must rely only on glucose, a type of sugar. Although glucose is a good source of energy, there is a limited amount available. When all the glucose has been used up, the body tries to use fat for energy, but can't. This leads to low blood sugar and to the build up of harmful substances in the blood.

What are the symptoms?

Some of the first symptoms are extreme sleepiness, behavior changes, irritable mood, and poor appetite.  Children with MCADD usually get symptoms for the first time between three months and two years of age.  When children have symptoms, it's called a metabolic crisis.  A crisis can often be set off by an infection, so illness may start with symptoms of fever, diarrhea, and vomiting.  Low blood sugar then follows.  If a metabolic crisis is not treated, a child with MCADD can develop breathing problems, seizures, and coma, sometimes leading to death.

What is the treatment?

The baby's primary doctor will work with a metabolic specialist to develop an individual treatment plan for the baby.  A dietician familiar with MCADD may also help develop that treatment plan.  Treatment can include:

  • Avoiding going a long time without food - Babies and young children with MCADD need to eat often to avoid low blood sugar or a metabolic crisis.  They may need starchy snacks before going to bed and first thing in the morning.  They may even need to be woken up during the night for another snack.
  • A special diet - Sometimes a low fat, high carbohydrate diet is recommended.
  • L-carnitine supplements - This is a safe and natural substance that helps the body make energy and helps the body get rid of harmful wastes.

Parents' Guide to MCADD (PDF)

Last modified on: 8/24/2010 2:13 PM