Medium-chain acyl-coenzyme A dehydrogenase (MCAD) deficiency is the most common fatty acid β-oxidation disorder and a prevalent metabolic congenital error It is often identified through newborn screening. Although children are normal at birth, symptoms usually emerge between three months and two years of age, with some cases appearing in adulthood.
Medium-chain acyl-CoA dehydrogenase (MCAD) plays a crucial role in mitochondrial fatty acid β-oxidation, a process vital for generating energy during extended fasting or high-energy demand periods. This process, especially important when liver glycogen is depleted, supports hepatic ketogenesis. The specific step catalyzed by MCAD involves the dehydrogenation of acyl-CoA. This step converts medium-chain acyl-CoA to trans-2-enoyl-CoA, which is then further metabolized to produce energy in the form of ATP. 
* Affected children, who seem healthy initially, may experience symptoms like low blood sugar without ketones (hypoketotic hypoglycemia) and vomiting
* Can escalate to lethargy, seizures and coma, typically triggered by illness
* Acute episodes may also involve enlarged liver (hepatomegaly) and liver issues
* Sudden death
* Administering simple carbohydrates
* Avoiding fasting
* Frequent feedings for infants
* For toddlers, a diet with less than 30% of total energy from fat
* Administering 2 g/kg of uncooked cornstarch at bedtime for sufficient overnight glucose
* Preventing hypoglycemia, especially due to excessive fasting.
* Avoiding infant formulas with medium-chain triglycerides as the main fat source