POLG and Parkinson disease: This study investigates the contribution of key NRE-associated genes—ATXN2, ATXN3, CACNA1A, TBP, C9ORF72, PRNP, POLGA, and TOMM40—to PD in a Swedish cohort, examining their influence on clinical phenotype and associated molecular signatures to better characterize the overt stages of the disease.