Parkinson’s disease is a neurodegenerative movement disorder that progresses relentlessly. It gradually impairs a person’s ability to function until they ultimately become immobile and often develop dementia. In the U.S. alone, over a million people are afflicted with Parkinson’s, and new cases and overall numbers are steadily increasing.
There is currently no treatment to slow or halt Parkinson’s disease. Available drugs don’t slow disease progression and can treat only certain symptoms. Medications that work early in the disease, however, such as Levodopa, generally become ineffective over the years, necessitating increased doses that can lead to disabling side effects. Without understanding the fundamental molecular cause of Parkinson’s, it’s improbable that researchers will be able to develop a medication to stop the disease from steadily worsening in patients.
Many factors may contribute to the development of Parkinson’s, both environmental and genetic. Until recently, underlying genetic causes of the disease were unknown. Most cases of Parkinson’s aren’t inherited but sporadic, and early studies suggested a genetic basis was improbable.
Nevertheless, everything in biology has a genetic foundation. As a geneticist and molecular neuroscientist, I have devoted my career to predicting and preventing Parkinson’s disease. In our newly published research, my team and I discovered a new genetic variant linked to Parkinson’s that sheds light on the evolutionary origin of multiple forms of familial parkinsonism, opening doors to better understand and treat the disease.
Genetic linkages and associations
In the mid-1990s, researchers started looking into whether genetic differences between people with or without Parkinson’s might identify specific genes or genetic variants that cause the disease. In general, I and other geneticists use two approaches to map the genetic blueprint of Parkinson’s: linkage analysis and association studies.
Linkage analysis focuses on rare families where parkinsonism, or neurological conditions with similar symptoms to Parkinson’s, is passed down. This technique looks for cases where a disease-causing version of the gene and Parkinson’s appear to be passed down in the same person. It requires information on your family tree, clinical data and DNA samples. Relatively few families, such as those with more than two living, affected relatives willing to participate, are needed to expedite new genetic discoveries.
“Linkage” between a pathogenic genetic variant and disease development is so significant that it can inform a diagnosis. It has also become the basis of many lab models used to study the consequences of gene dysfunction and how to fix it. Linkage studies, like the one my team and I published, have identified pathogenic mutations in over 20 genes. Notably, many patients in families with parkinsonism have symptoms that are indistinguishable from typical, late-onset…
