Q. A 1-month-old boy is brought to the pediatric emergency department by his parents due to poor feeding and excessive sleepiness over the past few days. The parents mention that he has had slow weight gain and persistent vomiting since birth. On examination, the child is lethargic, has poor muscle tone, and appears dehydrated. His breathing is rapid and deep. Laboratory evaluation reveals metabolic acidosis with an increased anion gap, ketosis, and hypoglycemia. His ammonia level is also found to be elevated. Based on this child's clinical presentation and laboratory findings, what is the most likely diagnosis?