A well, 2-year-old girl presents to the clinic with symptoms of a viral illness. Her parents report she has had bouts of vomiting and diarrhea over the last 24 hours. This morning they could barely wake her from her crib and she was very weak. Laboratory tests show low blood glucose (hypoglycemia) and elevated liver enzymes. There are no ketones present in her urine. The child is hospitalized and glucose is administered by I.V. Additional laboratory analysis showed elevated medium-chain fatty acyl carnitines in blood and 6–8 carbon dicarboxylic acids in the urine. Which of the following abnormalities is the most likely diagnosis for this child?