PRKN and Parkinson disease: The remaining 5–10% PD cases are caused by genetic mutations and loci with causative mutations in six genes and a number of additional unidentified genes have been associated with autosomal dominant or recessive PD.6 The autosomal recessive mutations in the Parkin gene (PARK 2) that encode an E3 ubiquitin ligase are the most common cause of early onset PD.