Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an inherited metabolic disorder in which the body is unable to break down certain forms of fat to produce energy.

Enzymes help to break down food that we eat, and certain enzymes break down fats into their building blocks – fatty acids.

Fatty acids are built like chains and come in many lengths such as short, medium, long or very long. The enzyme called medium-chain acyl-CoA dehydrogenase is in charge of breaking down medium-length fatty acids.

In individuals with MCADD, this enzyme is either missing or not working properly. Hence, they are unable to turn medium-length fatty acids into energy.

This is harmful as fat is needed for energy when their body runs out of sugar, such as during prolonged periods without food (fasting) or illness. In such instances, as the body is unable to utilise fat as a source of energy, the individual is at risk of becoming very sick.

How common is MCADD?

MCADD is one of the most common fatty acid oxidation disorders. It is estimated that one in 5,000 to 12,000 infants are born with MCADD.