In addition, there is a debate on the role of monoallelic mutations in the PRKN gene; indeed, while some authors have suggested an association with an increased risk of PD [75,76]; other recent cohort studies have pointed out that heterozygous pathogenic PRKN mutations are common in the population but do not increase the risk of Parkinson’s disease [77,78]. Here, PRKN is linked to Parkinson disease.