This Small Gene Edit In The Brain Could Stop Parkinsons
A new study published in the journal Nature on Wednesday shows that gene therapy on mice could be used to boost the effects of existing drugs used to treat Parkinsons disease, especially in late stages. And to boot, another arm of the study confirmed suspicions of how Parkinsons starts, which could one day help scientists identify people who could be vulnerable to developing Parkinsons five to 10 years before the onset of symptoms.
Parkinsons disease is thought to arise due to the loss of neurons in the brain that produce dopamine, a neurochemical that plays many different roles as a signal to other nerve cells. Dopamine is probably best known as the feel-good chemical thats associated with pleasure and reward. But its also critical in motor control. As these neurons fail and die, dopamine levels tank, and Parkinsons symptoms can worsen.
One way doctors treat Parkinsons is through prescribing a drug called levodopa, which the bodys neurons can convert into dopamine to restore levels to some degree of normalcy. But as the disease progresses, more and more neurons die before they can run this conversion, severely impeding the efficacy of levodopa in late-stage Parkinsons.
This discovery helps us construct a causal chain of events that could explain the long course of the disease, said Surmeier. It points to ways in which we might slow or stop disease progression.
When Should Genetic Testing Be Done
Your physician may suggest it if your Parkinsons diagnosis comes at a young age , if multiple relatives in your family history have also been diagnosed with the same, or if you are at high risk for familial Parkinsons based on your ethnicity .
However, what is the benefit of having the testing done at the present time? The information may be important for family planning for some individuals although as I said even if the gene is passed on it does not necessarily equal development of the disease. The risk, though, is higher in dominant genetic mutations versus recessive ones, on average if a person has a first-degree relative with Parkinsons their risk of developing the disease is 4 to 9 percent more than the general population.
Keep in mind that currently for the person being tested, there is no change in the treatment of their Parkinsons disease based on genetic findings. In the future, however, when there are treatments to slow down the onset of the disease or to prevent it from developing at all, then the identification of those people at risk will be very important.
What Is A Genetic Counselor
Genetic counselors provide education and support to people who are considering or have undergone genetic testing, including people who have Parkinsons, are at risk for the disease , or are just curious about their genetics and health. Genetic counselors also can talk you through specific considerations or questions surrounding employment, insurance, family and cost.
Learn more about genetic counselors in Chapter 3 of our guide to Navigating Clinical Trials.
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Benefits For Qualifying Patients
As part of the program, qualifying participants will receive free at-home DNA testing.
Patients will receive a free explanation of their genetic results from a qualified genetic counsellor if they test positive for the genetic mutation.
Have the chance to participate in research from home.
People who test positive for the genetic mutation and complete this program will automatically have the chance to be assessed for eligibility to take part in a planned future precision medicine treatment study.
How Do Lrrk2 Gene Mutations Cause Parkinsons Disease
Healthy Individuals withoutLRRK2 Parkinsonâs disease
All humans have two copies of theLRRK2 gene which produce LRRK2 protein. In healthy people both copies of the gene are normal and therefore produce normal LRRK2 which regulates normal cellular biology.
Patients withLRRK2 Parkinsonâs disease
Patients withLRRK2 Parkinsonâs disease usually have one normal gene and one mutated gene. This means that patients produce both healthy LRRK2 protein and an overactive form of LRRK2 protein. The overactive LRRK2 is believed to drive neurodegeneration, causing Parkinsonâs disease, while the healthy LRRK2 continues to provide normal regulation to cells in other organs such as the lungs and kidneys.
Patients withLRRK2 Parkinsonâs disease â Non specific inhibition
In order to slow or stop the disease, ESCAPE Bio believes that overactive LRRK2 needs to be nearly fully inhibited. However, if healthy LRRK2 is also inhibited by the same amount then it may not be able to regulate cellular function in other organs, thereby driving histopathological changes in the lung and kidney, which are hard to detect and may be associated with irreversible pathology if they go unchecked.
Patients withLRRK2 Parkinsonâs disease â ESCAPEâs approach
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Who Should Consider A Genetic Test For Parkinsons
There are two groups of people who might consider getting genetic testing and we will discuss each group separately.
Genetic testing for PD is a common request and a number of commercial labs perform panels of genetic testing for PD. You may ask: How can I test myself for Parksinons? Whether youre considering getting a genetic test through your doctor, or performing one at home, its important to note that at-home test dont map the entire gene for mutations. Genetic testing through your doctor will test for GBA, PARK7, SNCA, LRRK2, parkin and PINK1.
Both groups are faced with two questions: Should I get genetic testing? And if so, what should I do with the results? Before we address these two questions, we need to learn more about the complexity of genetic testing in PD.
Can Parkinsons Be Passed From Parent To Child
Its rare for Parkinsons disease to be passed down from parent to child. Most cases of Parkinsons arent hereditary. But people who get early-onset Parkinsons disease are more likely to have inherited it.
Having a family history of Parkinsons disease may increase the risk that youll get it. This means that having a parent or sibling with Parkinsons slightly increases the risk.
In most cases, the cause of Parkinsons disease remains unknown. But researchers have identified multiple risk factors that can increase your chances of getting this disease.
Risk factors for Parkinsons disease include:
- mutations in specific genes associated with Parkinsons
- having a family history of Parkinsons or a first-degree family member with Parkinsons
- being older, especially above the age of 60
- exposure to herbicides and pesticides
- being assigned male at birth
- history of brain injury
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Why Should I Participate
As part of the study, qualifying participants will receive free at-home genetic testing to determine if you have the G2019SLRRK2 mutation.
Get a free explanation of your genetic results from a qualified genetic counsellor if you test positive for the genetic mutation.
Have the chance to participate in vital research entirely from home.
People who test positive for the genetic mutation and complete this program will automatically have the chance to be assessed for eligibility to take part in a future precision medicine treatment study.
Referral To A Specialist
If your GP suspects Parkinson’s disease, you’ll be referred to a specialist.
This will usually be:
- a neurologist, a specialist in conditions affecting the brain and nervous system
- a geriatrician, a specialist in problems affecting elderly people
The specialist will most likely ask you to perform a number of physical exercises so they can assess whether you have any problems with movement.
A diagnosis of Parkinson’s disease is likely if you have at least 2 of the 3 following symptoms:
- shaking or tremor in a part of your body that usually only occurs at rest
- slowness of movement
- muscle stiffness
If your symptoms improve after taking a medication called levodopa, it’s more likely you have Parkinson’s disease.
Special brain scans, such as a single photon emission computed tomography scan, may also be carried out in some cases to try to rule out other causes of your symptoms.
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New Diagnostic Standards For Parkinsons
Until recently, the gold-standard checklist for diagnosis came from the U.K.s Parkinsons Disease Society Brain Bank. It was a checklist that doctors followed to determine if the symptoms they saw fit the disease. But thats now considered outdated. Recently, new criteria from the International Parkinson and Movement Disorder Society have come into use. This list reflects the most current understanding of the condition. It allows doctors to reach a more accurate diagnosis so patients can begin treatment at earlier stages.
When Should A Person Seek Genetic Testing
Genetic testing is available for some genes related to Parkinsons disease, but testing may not provide useful information to individuals.
For one thing, a wide range of genes may play a role, and it is not possible to test them all. A person may also have a relevant feature but not go on to develop Parkinsons disease.
For example, only around 0.7% of people with symptoms of Parkinsons disease have changes in the LRRK2 gene, and around 0.3% have changes in the PRKN gene, according to a 2020 review.
Finding out in advance if a young person has the gene may help them prepare for the future if there is strong evidence of a family history of the condition. However, the results are unlikely to be conclusive and may cause unnecessary anxiety.
Anyone who is interested in genetic testing should discuss the pros and cons with a doctor and consider genetic counseling if they decide to go ahead.
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For Parkinsons Patients Genetic Testing May Open Possibilities
Physicians have had little incentive to order genetic tests for their Parkinsons disease patients, although evidence suggests that up to 15% of these cases may be genetic.
Mutations in several different genes increase the risk of Parkinsons disease, says Roy N. Alcalay, MD, MS, the Alfred and Minnie Bressler Associate Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons and a neurologist at NewYork-Presbyterian/Columbia University Irving Medical Center. Until recently, we rarely offered genetic testing for people with Parkinsons because the benefit had been unclear.
But recent studies have shown that genotype can help better estimate the rate of disease progression in Parkinsons. And as new drugs designed for people with specific Parkinsons genes have entered clinical trials , Alcalay realized the calculus has changed.
From our own genetic studies, I realized many people were eligible to enroll in such trials, but they didnt know it because nobody told them about their genetic status, Alcalay says. I wanted to find a simple, ethical way to offer Parkinsons patients information about their genotype if they are interested.
Alcalay, the principal investigator of PDGENEration, talked to the CUIMC Newsroom about how the program may help support the development of personalized therapies for Parkinsons patients.
Why is now the right time to start genetic testing in Parkinsons disease?
Should I Get Tested For Genetic Markers For Parkinson’s
You can find out if you have certain genetic markers for Parkinson’s disease with at-home genetic tests. However, Dr. Litvan is cautious about recommending genetic testing for everyone. Remember: Most people with the mutations linked to Parkinson’s never get the disease, so you may end up with a ton of unnecessary stress and worry if your results reveal one of these genetic factors.
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Genetic Testing Is Primarily For Research Not Care
Genetic testing as part of a research study is not necessarily intended to provide you with personal medical information and, in some studies, you may not learn your results. As of this writing, even if you discover that you do carry a genetic mutation, these results will not significantly alter your personal medical care. Some studies are testing new therapies in mutation carriers. Your genetic status may allow you to participate in research studies, partnering with scientists to add to our existing knowledge about brain disease and help evaluate new treatments.
The Decision To Seek Genetic Testing Is A Personal One
Learning you carry a gene mutation that raises disease risk can be concerning for you and your family. The decision to seek genetic testing or to participate in genetic research deserves extra attention. A genetic counselor is trained to talk with you and help you gain a fuller understanding of what your results might mean for you and your family.
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Genes Linked To Parkinsons Disease
Theres a long list of genes known to contribute to Parkinsons, and there may be many more yet to be discovered. Here are some of the main players:
SNCA: SNCA makes the protein alpha-synuclein. In brain cells of individuals with Parkinsons disease, this protein gathers in clumps called Lewy bodies. Mutations in the SNCA gene occur in early-onset Parkinsons disease.
PARK2: The PARK2 gene makes the protein parkin, which normally helps cells break down and recycle proteins.
PARK7: Mutations in this gene cause a rare form of early-onset Parkinsons disease. The PARK7 gene makes the protein DJ-1, which protects against mitochondrial stress.
PINK1: The protein made by PINK1 is a protein kinase that protects mitochondria from stress. PINK1 mutations occur in early-onset Parkinsons disease.
LRRK2: The protein made by LRRK2 is also a protein kinase. Mutations in the LRRK2 gene have been linked to late-onset Parkinsons disease.
Among inherited cases of Parkinsons, the inheritance patterns differ depending on the genes involved. If the LRRK2 or SNCA genes are involved, Parkinsons is likely inherited from just one parent. Thats called an autosomal dominant pattern, which is when you only need one copy of a gene to be altered for the disorder to happen.
Study Examines Genetics Of Parkinsons In Latinos
It also established the Hispanic Parkinsons Advisory Council in December 2019. Led by Mata, the groups goal is to increase Latino participation in PD GENEration. Since the councils inception, PD GENEration has doubled the percentage of Latino participants from approximately 3% to 6%.
Adding more Latinos and Parkinsons patients as a whole could help uncover the true share of those whose cause of disease is familial, environmental, or idiopathic, meaning the specific cause of the disease is unknown.
According to María De León, MD, a Latino woman with Parkinsons who participated in PD GENEration and who is a movement disorder neurologist, PD GENEration gives minorities more information about their disease than ever before. This knowledge will help them in the long run as new medicines are developed, she said.
Patients are then able to participate in further clinical studies and trials and do other treatments that could then lead to further information and developing the science and also perhaps, to a cure of any given subtype of Parkinsons thats caused by genetic difference, said Leon in the joint interview with Mata. Leon, 53, a resident of East Texas, also is part of the Hispanic Parkinsons Advisory Council.
Historically, its been estimated that Parkinsons is caused by genetic factors in about 10% of patients. But for the more than 2,000 people who have been tested through the initiative, that rate is closer to 15%16%.
Can I Be Tested
Tests are generally arranged through a healthcare professional who can then interpret the results and give advice on how the information can be used.
Genetic testing is now also available from a number of companies who deal directly with people being tested. This can have several implications:
- Your doctor is not automatically informed of results, allowing you to keep findings to yourself if you wish.
- Results will not automatically be passed to your insurance company, although you should check your policy as you may be required to reveal all genetic test information. Failure to do so could invalidate your cover.
- You may not get the opportunity to discuss your test results and their implications with an experienced healthcare professional.
Important! Thoroughly check the credentials of any company offering genetic testing, as not all provide a high standard of service.
Genes Connected To Parkinson’s
In 1997, researchers at the National Institutes of Health made the first Parkinsons genetic connection, discovering that mutations in the SNCA gene were common in several families who had many members with Parkinsons. While mutations in this gene are rare, they have taught us invaluable information about PD.
The SNCA gene instructs the body to make the protein alpha-synuclein, which for reasons that are not yet known, clumps in the brain cells of people with PD. Study of the SNCA gene led to this understanding that applies to nearly all people with the disease. Since then, alpha-synuclein has been a major target of new drugs for Parkinsons.
Another gene that plays a role in Parkinsons is LRRK2, which accounts for one to two percent of all cases. For people of particular ethnic backgrounds Ashkenazi Jewish and North African Berber descent mutations in the LRRK2 gene account for a much greater number of cases than in the general PD population. Mutations in LRRK2 lead to too much activity of the LRRK2 protein, though recent research indicates people without a mutation can also have overactivity of LRRK2.
Shake It Up are funding several studies into LRRK2 and you can learn more about these here.GBA
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