Question: How many people are affected by Dandy-Walker malformation ?
Answer: Dandy-Walker malformation is estimated to affect 1 in 10,000 to 30,000 newborns.
Source: GHR

Question: Is Dandy-Walker malformation inherited ?
Answer: Most cases of Dandy-Walker malformation are sporadic, which means they occur in people with no history of the disorder in their family. A small percentage of cases seem to run in families; however, Dandy-Walker malformation does not have a clear pattern of inheritance. Multiple genetic and environmental factors likely play a part in determining the risk of developing this disorder. First-degree relatives (such as siblings and children) of people with Dandy-Walker malformation have an increased risk of developing the condition compared with people in the general population. When Dandy-Walker malformation is a feature of a genetic condition, it is inherited in the pattern of that condition.
Source: GHR