Q. A 3-year-old boy is brought to the pediatrician by his parents who are concerned about his unusual facial appearance. They describe that his cheeks have been gradually becoming fuller over the past year. The parents also mention that their son often experiences episodes of extreme lethargy and difficulty concentrating. On physical examination, the physician notes a significantly large abdomen. Laboratory studies reveal severe hyperlipidemia, lactic acidosis, hyperuricemia, and persistent hypoglycemia. What is the most likely diagnosis?