Similar to Drosophila, it is characterized by a short life span, a quick change of generations with a large number of progeny, ease of cultivation, and a relatively small and well-studied genome that is highly homologous to the human genome, as 40%–50% of all protein-coding nematode genes have orthologs in the human genome, including the orthologs of several genes that cause monogenic forms of PD (LRRK2/lrk-1, PINK1/pink-1, PRKN/pdr-1, DJ-1/djr-1.1/djr-1.2, and ATP13A2/catp-6). The gene discussed is LRRK2; the disease is Parkinson disease.