LTBP4 and pulmonary arterial hypertension: Some other monogenetic lung disorder-related genes were enriched in specific SAE cell types, including BC (LTBP4, ELN, cutis laxa), ionoctyes (HPS5, Hermansky-Pudlak syndrome), mucin-producing cells (COL1A1, Ehlers-Danlos syndrome), and neuroendocrine cells (BMPR2, pulmonary hypertension; Supplemental Figure S2D-F).