A 5-year-old white female presented with coma and died unexpectedly. She ha
d a history of recurrent episodes of febrile illnesses associated with leth
argy and coma. Postmortem investigation revealed a fatty liver, leading to
a suspicion of inborn error of fatty acid oxidation, The diagnosis of mediu
m-chain acyl-CoA dehydrogenase (MCAD) deficiency was suggested by abnormal
acylcarnitine profile with increased octanoylcarnitine in the blood, and co
nfirmed by fatty acid oxidation studies and mutation analysis in skin fibro
blast cultures. This case emphasizes the need to consider fatty acid oxidat
ion disorders in all children who present with hypoglycemia with absent or
mild ketones in the urine and high anion gap metabolic acidosis.