Natural History Studies of Mucopolysaccharidosis III

Mucopolysaccharidosis (MPS) type III (Sanfilippo syndrome) is a group of four devastating genetic diseases that result in the abnormal accumulation of glycosaminoglycans in body tissues. In MPSIII the predominant symptoms occur due to accumulation within the central nervous system (CNS), including the brain and spinal cord, resulting in cognitive decline, motor dysfunction, and eventual death. In anticipation for future therapeutic studies for MPSIIIA and MPSIIIB, we are performing a natural history study to identify the following: 1. Individual rates of decline in motor and cognitive function in a cohort of potential clinical trial patients 2. The natural history of outcome measures in order to assess their appropriateness as outcomes in an eventual trial 3. Baseline functional data in patients who will be potential candidates for an eventual trial 4. Biomarkers of disease progression over a 12-month interval, including changes in brain MRI and in cerebrospinal fluid Patients in this study will need to come to Nationwide Children's Hospital in Columbus, Ohio, three times. At each of these three time points, cognitive outcome measures will be assessed: at baseline (visit 1), 6 months (visit 2), and at 12 months (visit 3). At baseline (visit 1) and 12 months (visit 3), an MRI and a lumbar puncture will be performed.