Simple chronic colitis model using hypopigmented mice with a Hermansky–Pudlak syndrome 5 gene mutation

Pigmentation in mammals is important for protection of skin and eyes from ultraviolet radiation. Dysregulation of pigmentation is often associated with other conditions that are not directly linked to pigmentation. Here, we isolated spontaneously occurring hypopigmented mice that occasionally experienced severe diarrhea during lactation. Treatment of these mice with dextran sulfate sodium salt, a conventional method to induce acute colitis, caused chronic diarrhea with granulomatous colitis. Gene mapping and sequencing revealed that the mice had a nonsense mutation in the Hermansky–Pudlak syndrome (Hps)5 gene. As some HPS patients can develop granulomatous colitis, the simple induction of chronic colitis in spontaneously mutated Hps5‐deficient mice may become an invaluable model for exploring treatment options in patients with HPS as well as other patients with inflammatory bowel disease.