Children and adults of all ages with various inherited neurological disorders may be eligible for this study. Participants will undergo a detailed medical and family history, and a family tree will be drawn. They will also have a physical and neurological examination that may include blood test and urine tests, an EEG (brain wave recordings), psychological tests, and speech and language and rehabilitation evaluations. A blood sample or skin biopsy may be taken for genetic testing. Depending on the individual patient s symptoms, imaging tests such as X-rays, CT or MRI scans and muscle and nerve testing may also be done.