[5][6] People with this disorder have inadequate levels of an enzyme that breaks down a certain group of fats called long-chain fatty acids.

[6] The presentation of mitochondrial trifunctional protein deficiency may begin during infancy, features that occur are: low blood sugar, weak muscle tone, and liver problems.

These fatty acids are stored in the body's fat tissues and are a major source of energy for the heart and muscles.

[10][11][12] Mutations in the HADHA or HADHB genes that cause mitochondrial trifunctional protein deficiency disrupt all functions of this enzyme complex.

Clinically, trifunctional protein deficiency usually results in sudden unexplained infant death, cardiomyopathy, or skeletal myopathy.