Gencer et al. investigated the gene polymorphisms of BER proteins in PD patients and healthy controls, and suggested that APE1, X-ray repair cross-complementing protein 1 (XRCC1), and X-ray repair cross-complementing protein 1 (XRCC3) genetic variants may be risk factors for developing PD, due to loss of dopaminergic neurons in the substantia nigra and locus coeruleus [60]. Here, XRCC1 is linked to Parkinson disease.