Documented causes of death included progressive multifocal leukoencephalopathy following administration of high doses of steroids for treatment of recurrent immune thrombocytopenia (n=1), pulmonary hypertension in the setting of progressive inflammatory lung disease (n=1), spontaneous brain hemorrhage secondary to untreated lymphoma (n=1), Pneumocystis pneumonia in a patient with CD4+ count less than 200 (n=1), and undifferentiated shock (n=1). This evidence concerns the gene CD4 and pulmonary arterial hypertension.