Q. A 2-month-old male neonate is brought to the pediatric clinic by his parents who are concerned about the baby's poor weight gain and abnormal stools. They report that the infant's stools are very foul-smelling and appear oily. On physical examination, the infant appears underweight and has pale, voluminous stools. Laboratory analysis reveals low serum triglycerides and low cholesterol, while stool analysis confirms the presence of fat. Genetic testing has been initiated. The family history reveals that the parents are second cousins. What genetic mutation is most likely responsible for this patient's condition?