The targeted deletion of the Dtnbp1 gene produced by the IMPC recapitulates the main features of Hermansky-Pudlak syndrome (HPS), a rare autosomal recessive genetic disorder affecting roughly 1/500,000 individuals worldwide, but disproportionately present in 1/1800 people in Puerto Rico18,19. The gene discussed is DTNBP1; the disease is Hermansky-Pudlak syndrome.