However, the role of heterozygous PRKN variants as causative or susceptibility factors for PD is still under vivid debate: two studies have found an increased risk for PD in carriers of heterozygous PRKN variants as compared to controls13,14, while two other studies with almost complete genotyping of PRKN for copy number and single nucleotide polymorphisms found that heterozygous PRKN variants do not contribute to overall disease risk15,16. This evidence concerns the gene PRKN and Parkinson disease.