What Your Test Results Mean:

Carriers typically show no symptoms of MCADD; however, carriers are at an increased risk of having a child with MCADD. Risk for the current or future pregnancies is dependent on your partner’s carrier status. Carrier testing of your partner is recommended in addition to consultation with a genetic counselor.

Disease Explained:

MCADD is an inherited metabolic disorder that prevents the body from converting certain types of fats into energy. MCADD is usually diagnosed in infancy or early childhood, when the affected individual presents with symptoms such as vomiting, low blood sugar, lack of energy, and failure to thrive. Partially metabolized fatty acids and accumulate in body tissues and cause organ damage if the disease goes untreated. The symptoms are especially noticeable when the individual goes for a long time between meals or suffers from a viral infection. Thus, it is important to ensure that children with MCADD eat frequent meals, preferably high in carbohydrates and low in fats. The prognosis of an affected individual depends on the severity of the symptoms, but is usually good if the disease is diagnosed early and careful medical management is provided. Management is typically overseen by a group of metabolic specialists.

How the Genetics Works:

MCADD is an autosomal recessive metabolic disorder caused by pathogenic variants in the ACADM gene. In general, individuals have two copies of the ACADM gene. Carriers of MCADD have a single variant in one copy of the ACADM gene while individuals with MCADD have variants in both copies of their genes, one inherited from each parent. Risk for two carriers to have a child with the disorder is 25%.