Dandy-Walker syndrome is a congenital brain abnormality characterized by malformations of the cerebellum and enlarged fluid spaces in the brain. It results from incomplete development of the cerebellum and cyst formation in the posterior fossa. Causes are largely unknown but may include genetic and environmental factors. Diagnosis is typically made through prenatal ultrasound or postnatal MRI showing cerebellar abnormalities and cyst formation. Treatment focuses on managing hydrocephalus through surgery if needed, along with physical therapy and monitoring for developmental delays. Prognosis varies depending on individual severity but can include lifelong challenges with coordination, learning, and other abilities.