Therefore, loss-of-function mutations in PINK1 and Parkin are the most common known causes of autosomal recessive and early-onset PD (before the age of 45; Kitada et al., 1998; Valente et al., 2004; Thomas et al., 2007; Houlden and Singleton, 2012; Giannoccaro et al., 2017; Figure 4). Here, PRKN is linked to Parkinson disease.