Image copyright French-speaking Brazilian newspaper PT Image caption Contrary to popular belief, mutations in this gene are well validated and have a high positive result rate
For the first time, scientists have identified early-stage genetic changes in mice that led to late onset Parkinson’s disease.
The researchers used genetic markers on mouse brain samples from the period when Parkinson’s disease takes hold.
This is important because if taken too early, the majority of Parkinson’s sufferers could be helped with treatment.
Though these genes only affect a small percentage of Parkinson’s patients, they can save lives.
The findings are published in the journal Nature Genetics and were led by scientists from the University of Zurich and the Stanford University School of Medicine.
The discovery was part of an ongoing research project aiming to unravel how a gene called Oticonin-1 (OM) increased a mouse’s vulnerability to the disease.
Early sign of Parkinson’s
Previously, Parkinson’s researchers knew that mice with a mutation in this gene died as early as six months of age. A mutation this early appeared harmless – until mice with an untreated version of the same gene died four months later.
“We proposed that Omaticonin-1 lead to Parkinson’s disease by virtue of being a risky gene, a hazardous gene,” says Dr Anne Vernazza, a post-doctoral fellow at the University of Zurich and first author of the study.
This hypothesis originally came from a 2004 study by a French lab, which found an earlier version of Parkinson’s disease in 21 mothers who carried the gene.
The French institute, led by Professor Elodie de Montrond, had only identified the risk in humans, so it made sense that Omaticonin-1 carried the same risk in mice.
The Swiss team and Professor de Montrond’s French laboratory sequenced the parts of the mouse brain where the gene is active, mapped out both the gene’s sequence and the path by which the gene functioned.
Image copyright AFP/Getty Images Image caption Parkinson’s affects around 1% of the world’s population
“Only two genes are clear as being a major risk factor, Omaticonin-1 and Gomexanthin receptor II (GTR2),” says Professor de Montrond.
This third type of gene, though not among the three that the French lab found, is known to affect Parkinson’s in humans. The US researchers made this discovery last year.
Whether this component will progress to humans has yet to be determined.
The three markers, the researchers believe, were clearly enough to confirm which genes are linked to the disease.
The first of these markers was Tritchler 1 (TRIK). It is the key SNP (single nucleotide polymorphism) associated with the Parkinson’s disease gene.
The team found that after three months, the mice with a high amount of TRIK had a nearly 100% chance of suffering from late onset Parkinson’s disease – about four years earlier than in the mice with a lower amount of TRIK.
Image copyright Getty Images Image caption Saluting the Queen will often lead to severe tremors
Image copyright Getty Images Image caption How quickly the disease progresses affects the ability to walk, talk and interact
The second marker seen in these studies is the Trichocholin1A gene (TRC2). This gene switches off the neurotransmitter dopamine in the brain. The barbiturates, which humans use to treat Parkinson’s disease, are made from it.
Because of these two genes, it is believed that TRC2 may be important in late onset Parkinson’s disease.
The scientists are now analysing the genes themselves and the genetic variants that vary across people in the hope of coming up with new treatments for the disease.
Of course, Parkinson’s patients who carry these same genes will die earlier than most people.
“They could be helped with therapy earlier than people with a mutation that is known to cause disease, which tends to happen later on in Parkinson’s,” says Dr Vernazza.
“This is an untapped niche of medicine, but we would still never encourage someone to test themselves because they may have small inherited risk factors for the disease.”