Below are three case scenarios. For each scenario determine: 1) Most likely enzyme deficiency and which amino acid(s) is no longer metabolized 2) If any amino acids become essential as a result of the deficiency 3) Potential vitamin supplements that may be useful for the condition and what steps in the metabolism they could potentially help with. Scenario 1: A full-term girl was born by normal vaginal delivery and was released from the hospital at three days of age. At nine days of age a screening test for branched-chain amino acids came back positive and the child was readmitted to the hospital for further evaluation. There was no history of any genetic disease in either family, and both older siblings were well. Scenario 2: A 69-year-old woman presented with a 30-year history of lower back and large joint pain of the hips and shoulders. On examination blue-grey, pigmented macules were present over the cartilaginous portions of the ears and on the sclera. Past medical history included aortic stenosis. Scenario 3: A 4-day old infant is being followed in your clinic. Her birth weight was 5.9 pounds and the pregnancy and birth (vaginal delivery) were normal. Results from newborn screening demonstrated a phenylalanine (Phe) level of 6.6 mg/dL (normal range: 1-2 mg/dL).