This study will examine the origin and development of certain neurological diseases involving abnormal metabolism. A significant number of patients with progressive neurological disorders have not been diagnosed despite extensive workups. Lack of a specific diagnosis may amplify the distress of both the patient and family and decrease the chance of obtaining effective therapy. This study will try to advance the diagnosis and management of such patients.

Patients with a metabolic neurological disease of unknown cause or one which presents an unusual or difficult management problem may be eligible for this study. This study does not include patients with known or suspected leukodystrophy.

Participants will undergo various procedures, including physical and neurologic examinations, blood and urine tests, and magnetic resonance imaging (MRI) to determine the extent and severity of disease. MRI scanning uses a strong magnetic field and radio waves to show structural and chemical changes in the brain. During the procedure, the patient lies on a table in a narrow cylinder containing a magnetic field. He or she can speak with a staff member via an intercom system at all times during the procedure. Patients will also have a lumbar puncture (spinal tap) to examine the cerebrospinal fluid (CSF), which bathes the brain and spinal cord. To obtain the fluid, a local anesthetic is administered and a needle is inserted in the space between the bones in the lower back where the CSF circulates below the spinal cord. A small amount of fluid is collected through the needle. Although spinal fluid will not be examined regularly, this test may be requested during some clinic visits.

X-rays, nuclear medicine scans and consultations may be obtained as needed. Other tests may include electroencephalograms (brain wave recordings), psychological tests, and speech and language and rehabilitation evaluations. A skin biopsy may be done to grow cells in culture for metabolic and genetic testing and to analyze the skin under a microscope. For the biopsy, an area of skin is numbed with an anesthetic and a small circular area is removed, using a sharp cookie cutter-type instrument.

First degree relatives (parents, children or siblings) of patients with a metabolic disorder of unknown cause will be asked to provide a blood sample for DNA studies to try to identify genetic basis of the disorder.

The study is expected to continue for 3 years, with yearly monitoring of patients for changes in neurological, ophthalmological and general medical status.