An adult patient with pulmonary arterial hypertension, a mutation, and leflunomide exposure.

Pulmonary arterial hypertension (PAH) is a poorly understood disease of the small pulmonary arteries. Pulmonary vascular remodeling and progressively rising pulmonary vascular resistance are hallmarks of the disease that ultimately result in right heart failure. Several genetic mutations, most notably in bone morphogenetic protein receptor type 2, have a causal association with heritable forms of PAH. Mutations in ( have been reported in adults and children with PAH, but whether is causally associated with PAH is debated. With this case report, we describe the clinical characteristics, comorbidities, and exposure history of an adult patient with PAH and multiple sclerosis who was found to have a missense mutation and exposure to leflunomide.