PRKN and Parkinson disease: After removal of cases with established Mendelian mutations across all known PD genes, 1.0% (66/6552) of PD cases were found to harbour single heterozygous PRKN PD-causing mutations [either heterozygous copy number variants (CNVs) or single nucleotide variants (SNVs), Table 1], compared with 0.6% (37/5693) of controls.