In most cases, the cause of Parkinson’s disease (PD) is unknown. Testing blood for genetic mutations (DNA changes) known to cause PD is usually negative, particularly in patients with no family history. There is increasing evidence, however, that DNA may differ in the brain and blood, due to “somatic” mutations. Somatic mutations are changes in genetic structure that are not inherited and may happen in early development or later in life. Somatic mutations might contribute to the development of PD, even if only present in a low proportion of brain cells. Evidence for such a process has been reported in some cases of Alzheimer’s disease.
We will continue our initial investigation of DNA from brains, looking specifically for mutations that have led to additional copies of the alpha-synuclein gene in different regions of brains from PD patients and healthy controls. As we expect that only a small proportion of brain cells may carry such mutations, we will use several complementary sensitive methods to ensure our results are correct.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Evidence of alpha-synuclein gene copy number gains in PD brain will indicate that changes in our genes can contribute to PD, even when there is no family history. We would then need to determine ways to find these mutations in tissues related to brain during an individual’s life. Early detection of such somatic mutations, which predispose to PD later in life, could allow effective treatment when preventative drugs are available.
We will provide the first definitive data on whether changes in the number of copies of the alpha-synuclein gene exist in the brain as a result of “somatic” mutations. A positive result will provide a totally new outlook into the causes of PD, and potential later additional opportunities for testing, while a negative result will imply that such mutations are unlikely to be common.