To investigate the role of PlGF in the development of HPS, we generated Plgf–/– rats using CRISPR-Cas9 technology by deleting a 663-bp sequence in Plgf. These Plgf–/– rats were viable and fertile, and did not exhibit any noticeable abnormalities. The gene discussed is PGF; the disease is Hermansky-Pudlak syndrome.