All of the following statements regarding Sturge weber syndrome are true, EXCEPT:

Mental retardation is seen in 60% cases of Sturge weber syndrome. It is an nonfamilial disease characterised by the presence of nevus flammeus on one side of face. 40% of patients with po wine stain develop choroidal hemangioma. They also develop leptomeningeal angiodysplasia of brain and meninges resulting in seizures (85%), mental retardation and cerebral atrophy.