Delayed diagnosis of fatal medium chain acyl CoA dehydrogenase deficiency in a child

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common of the inborn errors of fatty acid oxidation. Typically, the initial manifestations occur between 2 months and 4 years of age, when hypoketotic hypoglycemia is precipitated by the catabolic stress of an acute infection or prolonged fasting. The clinical spectrum of MCAD deficiency can be extremely varied and range from an asymptomatic state to Reye-like syndrome, coma and sudden unexpected death in early life. The diagnosis may be delayed resulting in fatal outcome. We describe a 5-year-old Caucasian female with MCAD deficiency, who presented to the emergency department with coma and died unexpectedly. She had a history of recurrent episodes of febrile sepsis-like illnesses associated with lethargy and coma. Postmortem investigation revealed a fatty liver leading to a suspicion of inborn error of fatty acid oxidation. The diagnosis of MCAD deficiency was suggested by abnormal acylcarnitine profile with increased octanoylcarnitine in the blood, and confirmed by fatty acid oxidation studies and mutation analysis in skin fibroblast cultures. This case emphasizes the need to consider fatty acid oxidation disorders in all children who present with hypoglycemia with absent or mild ketones in the urine and high anion gap metabolic acidosis.