Genetic Analysis of the Chiari I Malformation

The purpose of this study is to better understand the genetic factors related to the Chiari I malformation. In people with this abnormality, the lower part of the skull is smaller than normal. As a result, the lowest part of the brain, called the cerebellar tonsils, protrudes out of the hole at the bottom of the skull into the spinal canal. This study will try to discover the location of the genes responsible for the malformation. Candidates for this study are: 1) Patients with Chiari I malformation who also have a family member with the abnormality or a family member with syringomyelia (a cyst in the spinal cord that is often associated with the Chiari I malformation). 2) Family members of patients with the Chiari I malformation. Participants will have a medical history and physical and neurologic examinations. They will undergo magnetic resonance imaging (MRI) of the brain and cervical (neck) spinal cord to measure the size of the head and determine the presence of the Chiari I malformation and syringomyelia. A small blood sample (about 2 tablespoons) will be drawn for DNA studies relating to the Chiari I malformation.