Five of these (APLP2, EN2, IREB2, NGFB, SLC18A2) were not associated with Parkinson's disease or related disorders in several important genetic disorder databases, including the Online Mendelian Inheritance in Man (OMIM), Genetics Home Reference (GHR) [25], Genetic Association Database (GAD) [26], or the Parkinson Disease mutation database (MutPD) [27]. The gene discussed is APLP2; the disease is Parkinson disease.