Acyl-coa dehydrogenase, medium-chain, deficiency of

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a genetic condition that prevents a person's body from being able to break down a specific type of body fat to make energy. Most of the time, the body uses available fuels such as sugars to make energy. However, if a person is sick and not eating (fasting), dieting, or stressed, they may not be eating a normal amount of food to provide the body with those sugars. In these times, the body uses other sources of fuel such as fatty acids. A person with MCAD deficiency cannot break down these fatty acids and this causes medical problems during illness or fasting. This is called a metabolic crisis or metabolic decompensation. These problems may include problems eating, nausea, vomiting, diarrhea, a lack of energy (lethargy) or infants or children being very sleepy, low blood sugar (hypoglycemia), and liver problems. Without treatment, these medical issues can quickly turn serious and lead to heart problems, breathing difficulties, coma, or even sudden death. To be as healthy as possible, people with MCAD deficiency need to avoid going long periods of time without eating. They should also have an emergency plan if they become ill or are unable to eat. If diagnosed and started on an appropriate therapy, people with MCAD deficiency can often lead healthy lives with a normal life expectancy.

People with MCAD deficiency may experience their first symptoms when they are a baby or young child. In the past, MCAD deficiency was not often diagnosed until a baby was very sick or after they passed away from apparent sudden infant death syndrome (SIDS). Now testing at birth (newborn screening) happens in all states in the United States. A newborn screen that suggests a baby may have MCAD deficiency is one with high levels of a specific fat. This result is called "Elevated C8 (often also C6, C10, C10:1 and C8/C10)." Having a positive newborn screen with these high levels does not mean for sure that a baby has been diagnosed with MCAD deficiency, but doctors usually work closely with metabolic dietitians and medical geneticists as they learn more about the baby and do additional blood tests to confirm a diagnosis.

To find a metabolic dietitian specializing in diets for people with metabolic conditions like MCAD deficiency, visit the GMDI Find a Metabolic Dietitian webpage.

To find a medical professional nearby who can discuss information and testing, a medical geneticists can be found by asking your doctor for a referral or looking on the American College of Medical Geneticists website. Genetic counselors can be found on the National Society of Genetic Counselors website.