Chart data, height, weight, pulmonary function, dietary intake and a venous blood and urine sample will be collected at enrollment then every 3 months for 9 months. Choline supplementation will be from enrollment for 6 months, with follow up at 3 months post supplementation. To avoid additional hospital visits and blood draws, and to co-ordinate with pulmonary function, hematology, clinical chemistry tests as part of clinical care, each subject will be seen at routine scheduled clinic appointments, which are every 3 months.