Medium chain acyl CoA dehydrogenase (MCAD) deficiency is an inherited metabolic disorder that stops the body from converting certain fats to energy due to an ineffective enzyme, MCAD. Typically, children affected by MCAD deficiency have symptoms like vomiting, tiredness, and low blood sugar, usually triggered by illness. These symptoms can progress to seizures, breathing difficulties, liver disease, brain damage, coma, and death. Although this disorder usually appears in infancy or childhood, adult onset has been documented. Once the diagnosis is made, life expectancy for individuals affected with MCAD deficiency is excellent. Regular and frequent feeding as well as avoidance of fasting prevents symptoms from recurring. MCAD deficiency is caused by pathogenic variants in the ACADM gene.