Below is an instruction from Human. Write a response.
    ### Instruction:
    Is pulmonary arterial hypertension inherited ?
    ### Response:
    Pulmonary arterial hypertension is usually sporadic, which means it occurs in individuals with no known family history of the disorder. These non-familial cases are described as idiopathic pulmonary arterial hypertension. About 20 percent of these cases are caused by mutations in one of the genes known to be associated with the disease, but most of the time a causative gene mutation has not been identified.
    