Genetics aspects for diagnosis of Parkinson's disease in different populations

In recent times, the genetics of Parkinson's disease (PD) has been gradually unraveled through the increasing contribution of genetic research. Discovering genes following Mendelian inheritance, such as autosomal dominant alpha-synuclein (Park!) and LRRK2 (ParkS), or autosomal recessive Parkin (Park2), PINKJ (Park6) and DJI (Park?), has provided great insights into the pathogenesis of PD. Genes found to be associated with PD through investigating genetic polymorphisms or via the whole genome association studies suggest that such genes could also contribute to an increased risk of PD in the general population. Some enviromnental factors have been found to be associated with genetic factors in at-risk patients, further implicating the role of gene enviromnent interactions in sporadic PD. For clinicians facing a rapid progress of genetic understanding in PD, there may be confusion as to what genetic tests should be conducted clinically. What is the role of genetic testing for Parkinson's disease especially in early-onset and familial cases of Parkinson's disease? After a brief review of PD genetics, we will discuss the insight of new genetic discoveries to clinicians, the implications of ethnic differences in Parkinson's disease genetics and the role of genetic testing for general clinicians managing PD patients.