What are the Different Types of Fatty Oxidation Disorders?

Fatty oxidation disorders (FODs) prevent a person from properly obtaining energy from fats. This is a genetic disorder which can lead to a number of very serious health problems. There are a variety of different types of this disorder, including medium-chain acyl-CoA dehydrogenase deficiency (MCAD), very long-chain acyl-CoA dehydrogenase (VLCAD) and trifunctional protein deficiency (TFP). Without treatment, fatty oxidation disorders in children may cause seizures, brain damage and severe respiratory stress. Episodes of coma and cardiac arrest may even cause death.

Fatty oxidation disorders occur as the result of mutated genes causing a reduction in the number of enzymes needed to break fats down into usable energy. Although fatty oxidation is genetic, a parent may only be a carrier for this disorder group and may be unaware of the possibility of passing it to offspring. It takes two genes, however, for fatty oxidation disorders to occur, which means that each parent must pass this gene to the child in order for a child to be affected. If only one parent passes the gene and the other does not, the child will also be a carrier, but will not be impacted by the disorder’s symptoms.

MCAD occurs as the result of a missing enzyme. Individuals with MCAD will show symptoms in infancy and early childhood, although some are not officially diagnosed until later in life. Symptoms include fatigue, loss of appetite, the sudden onset of an ear infection, vomiting or a sudden onset of cold or flu symptoms after appearing to be completely healthy. When not detected in infancy, MCAD is sometimes misdiagnosed and may be fatal if not recognized early enough. Historically, doctors were largely unaware of the presence of MCAD, but many children are now routinely tested for this fatty oxidation disorder immediately following delivery.

Like MCAD, TFP will present similar fatty oxidation disorder symptoms in infancy or early childhood. Other symptoms may include a lack of response to pain in infancy, irritability, clammy skin, muscle weakness and delays in walking. While children with these disorders may rely on glucose for sustained energy, a loss of appetite common in children with FODs can bring blood sugars dangerously low and trigger an episode of moderate to severe symptoms.

In VLCAD, symptoms occur as blood sugar levels decline. As a result of this decline, long-chain fatty acids do not break down, which results in too many of them being present in the body. This overpopulation can cause heart muscles to weaken and enlarge. These symptoms create a chain reaction by also interrupting the heart’s rhythm and causing damage to other vital organs, such as the kidney and the liver, which are wholly reliant on optimal blood circulation for functioning.