Pathogenic mutations in different PD-related genes with autosomal dominant or autosomal recessive Mendelian inheritance (LRRK2, VPS35, DNAJC13, SYNJ1, TMEM230, RAB39B) are involved in endosomal trafficking, indicating that DA neurons are specifically susceptible to endosomal dysfunctions (36). The gene discussed is RAB39B; the disease is Parkinson disease.