Dandy-Walker malformation-postaxial polydactyly syndrome is a rare genetic disorder that affects the development of the brain and the hands. It is characterized by an enlarged posterior fossa, a cyst in the fourth ventricle, and postaxial polydactyly (extra fingers or toes). It is caused by a mutation in the DANDY-WALKER gene, which is responsible for the development of the brain and the hands. Symptoms of this disorder can include developmental delays, intellectual disability, seizures, and vision and hearing problems. Treatment typically involves surgery to correct the malformation and physical and occupational therapy to help with any developmental delays.