Clinicogenetics of Parkinson′s disease: A drawing but not completed picture

Parkinson′s disease (PD) is a prevalent neurodegenerative disorder mainly affecting the population over the age of 60 years. The past decade has seen rapidly emerging data supporting a major importance of genetic factors in the development of PD. Increasing number of large-scale and replicating association studies has facilitated the confirmation of the possible predisposing factors to PD and the selection of genetic variants for risk prediction. While evidences are accumulating that variations within the SNCA, LRRK2, MAPT and GBA genes increase the individuals′ vulnerability to PD, inconclusive or negative results have been reported for an association between PD and variants of the parkin, PINK1, DJ-1, UCH-L1, Omi/HtrA2, GIGYF2, PLA2G6, VPS35, EIF4G1 and BST1 genes. However, our understanding of the genetic picture of PD remains preliminary. Molecular diagnosis of the disease is only recommended for cases with clear family history, and currently, there is no ideal genomic biomarker available to predict the disease onset and progression, or to make a molecular classification of the disease. Efforts are expected to identify more genetic predisposing factors and to further clarify their roles in the mechanisms of PD.