Study Rationale:
Epigenetic processes (changes in gene expression), such as DNA methylation (mechanism that cells use to control gene expression), ensure proper functioning of genetic materials in cells. Our previous studies found abnormal DNA methylation in blood samples from individuals with Parkinson's disease (PD). These changes may be associated with the disease and may also serve as potential biomarkers of PD. Biomarkers are molecules that can be used to track disease activity and can be easily measured from body tissues, such as blood. Biomarkers represent a promising diagnostic tool to aid in the earlier diagnosis of PD, in the tracking of disease progression and in determining whether new treatments are effective. However, there are no known biomarkers for PD, despite extensive efforts to identify them.
Hypothesis:
Our goal is to study changes in DNA methylation in a large group of participants with PD to discover a specific signal that could be used as a biomarker for this disease.
Study Design:
We will compare the pattern of DNA isolated from blood samples from 200 participants with PD and 200 healthy participants from the Harvard Biomarkers Study. We will investigate more than 450,000 markers in the genome. Once we detect the genes that have the greatest number of changes in the PD samples, we will select the ones that can better differentiate an individual with PD from an individual without PD to generate a diagnostic panel. We will repeat the study with blood samples obtained two years later to monitor how this signal changes as the disease progresses.
Impact on Diagnosis/Treatment of Parkinson's Disease:
Proper diagnosis of PD is usually achieved when motor disturbances are evident. However, by that time, many cells have already been lost. Our work aims to identify a unique molecular signature of PD that might help with an accurate diagnosis that can be easily performed on a blood sample. If DNA alterations are evident during the first stages of disease progression, this feature might serve as an early diagnostic tool.
Next Steps for Development:
Once we identify a set of markers that are highly specific to people with PD or that are predictive of the rate of PD progression, we will validate the performance of the panel on an independent group of cases. We will then seek paths to develop a diagnostic test that can be used in the clinic.
Final Outcome
No practical, definitive biomarkers -- objectively measurable characteristics -- of Parkinson's disease (PD) have yet been identified. This not only affects Parkinson's care options today but also stands in the way of the development of better treatments for the future. In the past, we studied the addition of chemical methyl to DNA in a process known as methylation as well as the use of changes in methylation as a biomarker for PD. We demonstrated changes in methylation in the blood in a small group of people with Parkinson's. In the most recent study, we sought to expand these findings using a much larger group of participants. We also tested blood samples from the people with PD who participated in the original study to evaluate changes in methylation over time. We confirmed that DNA methylation is indeed altered in people with PD and that methylation changes with disease progression. These findings lay the foundation for the development of a biomarker of Parkinson's disease.
September 2017