Although bronchial arterial hypertrophy with abnormal bronchial-to-pulmonary anastomoses has been observed in chronic thromboembolic pulmonary hypertension (CTEPH), BMPR2 mutations appear to generate unique singular millimetric fibrovascular lesions (SiMFis) affecting larger bronchial arteries of 1–2 mm in diameter [95]. The gene discussed is BMPR2; the disease is chronic thromboembolic pulmonary hypertension.