Subjects will be hospitalized on the General Clinical Research Center (GCRC) ward of Shands Hospital for 2-4 days every three to six months. A parent or legal guardian will be expected to stay with the subject. During that hospitalization, physical and intellectual development will be measured by standard tests. The GCRC dietician will ask questions about current diet at each visit and record answers. A general medical history and physical examination (including gross motor function and/or strength tests) will be performed during each visit as well as a six minute walking test. While enrolled in this study, a special "nutritional cocktail" and a Centrum-like multivitamin supplement will be provided for subjects to take daily. The nutritional cocktail has vitamin C, up to 10 mg/kg/day (max. 400 mg/day), riboflavin, up to 2.5 mg/kg/day (max. 100 mg/day), thiamine, up to 2.5 mg/kg/day (100 mg/day), carnitine, up to 10 mg/kg/day (max. 400 mg/day). The nutritive cocktail is in capsule form and the number of capsules that the subject will take will be based on body weight (for every 4 kg. of body weight subjects will receive 1 capsule daily). Each capsule contains: Vitamin C 40 mg, Riboflavin 10 mg, thiamine 10 mg and carnitine 40 mg. The maximum amount of capsules that will be given daily to anyone in this study is 10 capsules daily. A parent or legal guardian will be asked to complete each of eight questionnaires regarding behavioral and developmental, quality of life (5), and sleep. The behavioral and developmental, four of the quality of life (QOL) questionnaires, and the sleep questionnaire should be completed at the 0, 6 and 12 month visits. One of the QOL questionnaires (46 questions) will need to be completed monthly and mailed back to the study center after completion (self-addressed, stamped envelopes will be provided by the study and given to you by the coordinator). We expect that it will take up to 20 minutes to complete the monthly QOL questionnaire and up to 3 hours at the 0, 6 and 12 month visit to complete the rest of the questionnaires.