Parkinson’s disease is a neurological disorder that is characterized by a resting tremor, slow movement, muscle rigidity, and stooped posture. For this reason, it has been classified as a “movement” disorder, placing it in the same category as Huntington’s disease, another devastating movement disorder. Similar to Huntington’s, PD affects neurons that secrete the neurotransmitter dopamine. Specifically, in Parkinson’s, neurons that secrete dopamine degenerate, disrupting the circuit that these neurons usually participate in, ultimately causing the classic movement impairments associated with the disease. Despite the prevalence of PD and the research effort aimed at understanding the disease, many of the underlying causes remain unknown. However, the body of research that has been done to date, suggests that the genetics underlying PD development are quite complex.
In the issue of Nature Genetics published last week, researchers identified six new risk loci associated with Parkinson’s disease (PD). In the study, the team of researchers did a meta-analysis, a method which involves looking at and comparing results from a list of related studies, that covered more than 13,000 PD cases and almost 100,000 controls. In this larger sample, 26 gene loci were identified as having a significant association with PD, a result that highlights the genetic complexity of PD risk and development.
As this original pool of risk loci was so large, the researchers decided to try and figure out which of the original 26 loci were actually relevant to PD risk by looking at an independent sample series. They wanted to see which of the loci were again identified in this new series. In this later analysis, only 5,353 PD cases and 5,551 control cases were analyzed as a result of ensuring the samples were of high-quality, based on the criteria set by the group. Out of the 26 loci that were tested, 22 were replicated. Interestingly, 6 of these loci were new. The new risk loci include SIPA1L2, INPP5F, MIR4697, GCH1, VPS13C, and DDRGK1.
This study highlights the genetic complexity associated with PD as well as the new insights that can be gained despite related data that has already been reported. Not only were the authors able to confirm risk-associated loci that have already been published, a finding always beneficial to the field, they were able to identify the 6 new loci mentioned above, a finding that could lead to a variety of new studies and questions aimed at understanding the role of these new loci in the development of Parkinson’s disease.