Fallon et al. demonstrated that endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in the lungs play an important role in HPS pathogenesis.[5]–[9] Fallon et al. also reported that angiogenesis plays a role in the pathophysiology of HPS and explained the mechanisms underlying the activation of vascular endothelial growth factor A (VEGF-A), which is produced by inflammatory cells such as intravascular monocytes and induces angiogenesis.[10]. This evidence concerns the gene NOS3 and Hermansky-Pudlak syndrome.