AP3B1 and Hermansky-Pudlak syndrome: Moreover, although hemophagocytic lymphohistiocytosis (HLH) patients, which show excessive immune activation, are reported to have mutations in AP3B1 [184,185], HPS patients or pearl mouse models rarely display HLH symptoms [186,187], indicating that AP3B1 variation might have different effects depending on the mutation and/or species affected.