What exactly causes dandy walker syndrome? My cousin has this syndrome and i'd like to know more about it.

Dandy. Dandy walker syndrome is a complex anatomical birth defect that affects about 1 in every 30000 live births. It is named after the doctors who first described it. Symptoms may include delayed motor development (for example, a child that doesn't crawl at the right age or walk at the right age), bulging of the fontanelles, enlargement of the head, abnormal eye movements, and abnormal breathing patterns. The anatomical defect has several features. The first is the impaired development of part of the cerebellum (a part of the brain that seems to coordinate movements, among other things). The second is enlargement of the fourth ventricle (a fluid filled space in the lower, back part of the brain). The third is the enlargement of the posterior fossa (a part of the skull). Dandy walker syndrome is often accompanied by hydrocephalus (enlargement of the fluid-filled cavities in the brain that increases pressure inside the head), and other birth defects involving the brain, heart, and other body parts. The dandy walker birth defect probably starts very early in development, possibly as early as 7 weeks into the pregnancy. Recent scientific research suggests that genetic mutations may contribute. However, it is probably safe to say that no one knows exactly why people get dandy walker malformation.
Born with it. Congenital malformation of the brain. Many people on MRI have dandy-walker variants which are usually asymptomatic.