This study will screen patients with cerebellar ataxia to check for antibodies that indicate allergy to gluten (wheat protein) and will study the effect of a gluten-free diet in patients with these antibodies. Patients with cerebellar ataxia have problems with coordination, resulting in "clumsiness" and unsteadiness of posture and walking.

There are many known causes of cerebellar ataxia, but in many patients the cause is unknown and there are no available treatments. Cerebellar ataxia has been recognized as a complication of celiac disease, a syndrome characterized by sensitivity to gluten. Recognizing gluten sensitivity in patients with cerebellar ataxia would be important for two reasons: it would be one of the rare causes of the disease that are potentially treatable, and it would identify patients at risk for developing gastrointestinal cancers, particularly intestinal lymphoma.

Patients with cerebellar ataxia of known or unknown cause and normal healthy volunteers of any age are eligible for this study.

All participants will have a medical history, physical examination, blood drawn (30 milliliters, or 2 tablespoons) to check for celiac disease antibodies, and possibly other lab tests. This completes the participation of normal volunteers.

All patients will have magnetic resonance imaging (MRI) of the brain. This diagnostic tool uses a strong magnetic field and radio waves instead of X-rays to show structural and chemical changes in tissues. During the scanning, 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. Scanning times vary from 20 minutes to 2 hours.

Patients who have celiac disease antibodies will have an upper gastrointestinal (GI) endoscopy intestinal biopsy. For this procedure, a flexible tube is inserted into the mouth and down the throat into the stomach and duodenum (the upper part of the small intestine), where a small tissue sample is taken for microscopic examination. Patients with these antibodies will be put on a gluten-free diet and will be followed at NIH every 3 months for 12 months. On the first visit, patients will have their ataxia evaluated using NINDS's ataxia scale and will meet with a dietitian for instructions for a gluten-free diet. On the second through fifth visits (after 3, 6, 9 and 12 months, respectively, on the gluten-free diet), patients will have their ataxia evaluated, speak with a dietitian to assess their nutritional status, weight, and compliance with the diet, and provide a blood sample for celiac disease antibody testing.

At the completion of the study, patients may choose to continue or stop the gluten-free diet. If the ataxia assessments show improvement, patients will be advised to continue the gluten-free diet permanently.