A key driver of patients’ well-being and clinical trials for Parkinson’s disease (PD) is the course the disease takes over time. However, nearly all that is known about the genetics of PD is related to susceptibility—a person’s risk for developing the disease in the future. A new study by investigators from Brigham and Women’s Hospital published in Nature Genetics uncovers the genetic architecture of progression and prognosis, identifying five genetic locations (loci) associated with progression. The team also developed the first risk score for predicting progression of PD over time to dementia (PDD), a major determinant of quality of life.