The Cox team will leverage Perlegen's high-density array technology and the Mayo Clinic's extensive patient database, clinical expertise and DNA bank to create a genetic map of causes and risk factors for Parkinson's disease. To accomplish this, the team will compare DNA from 500 sibling pairs, one of whom has PD and one of whom does not. (The siblings are 'discordant' for PD.) Perlegen will use 200,000 unique genetic markers (SNPs) that are spread evenly across the human genome to identify those markers which vary most between PD and non-PD samples. After identifying these markers, they will be further analyzed in an additional population consisting of 300 individuals with PD and 300 well-matched, unrelated controls. We anticipate that at the end of one year, this two-tiered study will provide valuable insight into both susceptibility genes and risk factor profiles for PD. This information will increase our understanding of the genetics of PD and identify new targets for disease modifying therapies. We expect that this LEAP will significantly expand our knowledge-base of causes and risk factors for PD. New genes that play a role in PD might be identified, increasing both the understanding of the disease's cause and providing new therapeutic targets. Additionally, the findings will likely lead to a biomarker, or genetic test, of the disease. Overall, it will have an acceleratory effect on the field â€" identifying new therapeutic targets and, possibly, risk factors that can be modified behaviorally, or with drugs, to reduce the chances of developing PD.