MCAD Deficiency: Symptoms, Meaning, Treatment

Definition: what is an MCAD deficiency?

the Medium chain acyl-CoA dehydrogenase deficiency (MCAD) is a rare metabolic disease linked to genetic mutations that lead toinability of the body to use fatty acids as a source of energy. Since fatty acids are only partially used, an energy deficit occurs in certain organs. This chronic disease generally begins at birth and affects 1/26,000 births (according to data from the first year of screening in France, 2021). “Normally, when we are fasting or when the body needs a lot of energy because we play sports or because we are sick, our adipocytes (fat cells) will naturally release fatty acids into the blood. These fatty acids will be captured by the cells that will use them as a source of energy. In MCAD deficiency, this process that allows cells to use fatty acids is dysfunctional“, develops Dr. Jean-Baptiste Arnoux, pediatrician.

What are the symptoms of MCAD deficiency?

Most patients with an MCAD deficiency will not have never any symptoms of their disease, but they are at risk of having it under certain very specific circumstances. “Symptoms occur mainly in situations of high energy demand such as fever or prolonged fasting“, indicates the pediatrician specializing in rare diseases. The symptoms can be very serious: a hypoglycaemia, heart rhythm disturbances, liver failure, severe malaise which can leave scars. The organs suffer from not producing enough energy. In the absence of treatment and preventive measures, MCAD deficiency can be life threatening.

What causes an MCAD deficiency?

MCAD deficiency is a genetic disease linked to an abnormality of the ACADM gene which produces an enzyme called medium chain acyl-CoA dehydrogenase. “This enzyme deficiency is responsible for a decrease in energy production in the cells: the body is then unable to use fat as an energy source.“, details the specialist.

As of December 1, 2020, the MCAD deficit is detected during newborn screening (Guthrie test), at the same time as other genetic diseases, from a few drops of blood collected on a blotter taken at 3 days of life. If the result is normal, the parents will not be contacted. On the other hand, they will be contacted in the event of an anomaly, and referred to a pediatrician specializing in the disease.

It is necessary to avoid that the child is fasting more than 12 to 14H

What is the treatment for MCAD deficiency?

Treatment is mainly based on dietary measures. “If the treatment is followed correctly, the child can lead a normal life. is important to have very regular meals during the first year of life, every 3 hours at birth then we gradually expand so that by 12 months, we can allow 12 hours of fasting. Beyond that, parents are asked to try to prevent your children from fasting more than 12 to 14 hours when all is well. At the end of neonatal screening, children are referred to a specialized center (reference center or competence center for inherited metabolic diseases) where they will be monitored according to a national protocol.“, details Dr. Jean-Baptiste Arnoux. The younger the child, the greater the risk of decompensation. When the child is sick, has a fever (whatever the cause) or eats badly (whatever the cause), it is necessary to take glucose very regularly, even at night, and in large quantities. can go through a glucose-enriched drink regularly offered to the child at home, or even by a hospital infusion if the child cannot drink (vomiting) or has symptoms of decompensation (hypoglycaemia, etc.). Prevention of decompensation through simple dietary measures is at the center of concerns.

Thanks to Dr. Jean-Baptiste Arnoux, pediatrician at the Reference Center for Inherited Metabolism Diseases at Necker-Enfants Malades hospital.