Is Parkinson’s disease inherited?
There is a family history of Parkinson’s disease in 5 percent to 10 percent of patients. It may affect people of the same generation (e.g., a brother or sister) or in two generations, such as a father and son. Environmental toxins such as manganese, carbon monoxide and, rarely, certain pesticides cause diseases that resemble PD. However, most people with Parkinson’s disease have not been exposed to these toxins. In less than 1 percent of cases, PD is clearly familial (tends to occur among members of a family). Several gene mutations have been shown to cause Parkinson’s disease in a few families, but these have not been found in most people with PD. Studies of identical twins in which one twin was known to have PD showed no increase in the incidence of PD in the other twin compared to the general population of patients over the age of 60 years. However, among identical twins younger than 50, if one twin has Parkinson’s disease, there is an increased risk of PD in the other twin. This in
