The first gene identified as having a role in familial predisposition to Parkinson’s disease. Discovered in 1997 by researchers at the National Human Genome Research Institute (NHGRI) at the National Institute of Health (NIH), the alpha-synuclein gene is one of a cluster of similar genes located on chromosome 4; it regulates how the body makes and uses alpha-synuclein protein. This protein has a role in the function of neurons in the brain.
Only a handful of families have been found to have mutations of the alpha-synuclein gene, and in these families the mutations cause autosomal dom-inantly inherited Parkinson’s disease: The disease is passed from generation to generation with each child of an affected parent having a 50-50 chance of inheriting it. Notably the proportion of those people with the genetic mutation who develop the disease is much less than 100 percent, suggesting that additional nongenetic factors may be important in developing the disease even in people with the mutation.
The lewy body deposits that characteristically develop in the brain of people with Parkinson’s disease contain accumulations of alpha-synuclein protein; healthy brains do not have these deposits. The alpha-synuclein gene group already had been identified by scientists as having a key role in neuron activity in the brain. Researchers isolated a mutation, an error, in one pair of the 400 sets of genetic codes that the gene structure comprises. This tiny defect has significant implications for understanding of diseases such as Alzheimer’s and Parkinson’s that researchers hope will lead to more effective treatments as well as a possible cure or prevention.
Researchers are fairly certain that the alpha-synuclein gene mutation and other gene mutations since discovered do not themselves cause Parkinson’s disease, nor are they likely to be the sole focus of new treatment approaches. Most scientists still think that even with a genetic predisposition for
Parkinson’s disease, there are additional factors that cause the mutation to result in development of the disease. These factors are likely environmental as well as perhaps other genetic triggers.