Genetic Testing And Counseling
In contrast, EOFAD, with an age at onset before 60 to 65 years old, has an autosomal dominant mode of inheritance in which 20% to 70% of cases are estimated to have a PSEN1 mutation, 10% to 15% of cases are estimated to have an APP mutation, and PSEN2 mutations are rare., Indeed, approximately 60% of patients with EOAD have another known affected family member. The remaining 40% of patients with EOAD may lack a family history because of an early death of a parent, failure to recognize the disorder in family members, or, very rarely, a de novo mutation. If the parent of a patient with EOAD has a mutant allele, then the risk to the patients sibling of inheriting the mutant allele is 50%. The child of a patient with EOAD who carries a mutation has a 50% chance of transmitting the mutant allele to each of their children.
In this article, we have reviewed the genetics of AD. Further molecular genetic investigations should clarify the roles of additional known genes in the pathogenesis of both common sporadic as well as rare familial forms of AD. Already, investigations of the normal and aberrant functions of A protein and ApoE has provided insight into the underlying mechanisms for AD. Such research will continue to provide new strategies for therapeutic interventions.
Genes Heredity And Alzheimers Disease
Medical News Today explains that our genes determine what we look like, how we behave and how we survive. They can make us susceptible to certain diseases and conditions, like Alzheimers, depending on whether we develop those conditions.
How our genes interact with each other and on environmental factors has a large role in determining if we are likely to develop the disease, as does inherited traits, according to Healthline. People whose immediate family members have Alzheimers have been found to be at a higher risk of developing the disease.
Scientists believe Alzheimers results from a combination of genetic and hereditary traits, meaning some of these factors we can change, but others, such as our genes, we cannot. Here are two categories of genes that researchers have linked to Alzheimers:
Cause #: Genetic Mutations
Alzheimers disease isnt fully understood. Scientists believe that for most people, the disease has genetic, lifestyle, and environmental factors. All these factors may work together to create the right conditions for the disease to take root.
There is a hereditary component to Alzheimers. People whose parents or siblings have the disease are at a slightly higher risk of developing the condition. However, were still a long way from understanding the genetic mutations that lead to the actual development of the disease.
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Dementia And Down Syndrome
People with Down syndrome are born with an extra piece of DNA. This means they also have an extra copy of the APP gene. This leads to the build-up of amyloid plaques in the brain, which play a role in the development of Alzheimers disease. While not everyone with Down syndrome will go on to develop symptoms of Alzheimers, most people with the condition over the age of 40 will have amyloid build-up. It is estimated that about 50% of people with Down syndrome develop symptoms like memory loss, usually in their 50s and 60s.
To find out more about Down syndrome and dementia you can contact Downs Syndrome Association helpline on 0333 1212 300 or visit their website www.downs-syndrome.org.uk.
Red Flags To Consider Genetic Testing Or Genetic Consultation
Genetic testing for AD is only available for a small number of families with early-onset familial AD, with testing likely to be initiated in a living affected relative. If a gene mutation is found, other family members are eligible for testing for the identified family mutation. Clinical testing is currently not available for late-onset familial AD or sporadic cases. When there are multiple related affected individuals, research testing may be available. APOE e4 testing is not recommended for risk assessment because of low sensitivity and specificity.
Consider a genetics consult for patients with:
AD with age of onset < 60-65 years
Late-onset AD and multiple affected close relatives
Close relatives of the above two types of patients
A family member who has an identified mutation in the APP, PSEN1 or PSEN2 genes
to connect to your local genetics centre.
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Dementia With Lewy Bodies
The cause of dementia with Lewy bodies – clumps of protein in brain cells – is the same cause of Parkinsons.
Because it is closely related to Parkinson’s, and often has some of the same symptoms, it is possible the diseases share a genetic mutation.
But this is not clear.
Dementia with Lewy bodies usually occurs in people with no family history of the condition, although there have been very rare cases that seem to run in families, the NHS says.
The Latest In Alzheimers And Dementia Testing
There are many tests today that can help determine whether you are at risk for Alzheimers or dementia. These include:
- Cognitive assessments. Medical professionals continue to refine their ability to evaluate and assess a persons cognitive health with motor skill and mental tests.
- Brain scans. Brain imaging can also shed light on alterations in the brain that may lead to or be causing dementia.
- Blood tests. Tests can detect a protein in the blood called NfL . It has proven to be an early biological marker for Alzheimers. Other tests can evaluate the level of amyloid and tau proteins in the blood.
- DNA testing. There are many tests available today that can detect the ApoE gene which has been associated with late-onset Alzheimers. Even genealogy companies like 23andMe can test for variants of the ApoE gene.
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But How Can You Measure Lifestyle And Genetic Risk
The investigators hand-picked a list of common lifestyle factors, including smoking, alcohol consumption, physical activity, and diet, and created a score. A low score denoted a bad lifestyle. A high score denoted a good lifestyle.
However, taking this approach to measure lifestyle risk has several pitfalls:
- First, a vast number of factors comprise lifestyle and environment beyond smoking and physical activity. So any list may be arbitrary. In fact, our research team has argued that choosing a candidate list doesnt capture our complex lifestyles and may lead to false findings. For example, what exactly constitutes a healthy diet?
- Second, using a score makes the individual roles of the factors unclear.
- Third, if connections between factors influence both the score and dementia, then the score might be a weak proxy for other variables that werent considered. In other words, if weight is associated with diet and dementia, then it is hard to untangle the association of diet.
To create the genetic risk score, the investigators used all genetic variants previously identified by a genome-wide association study of Alzheimers disease. These gene variants are strongly associated with patients who have Alzheimers compared with healthy controls). Using this information, the researchers constructed a polygenic risk score.
Effect Of Genes In Other Types Of Dementia
Some types of dementia have links to other genetic malformations.
Huntingtons disease, for example, alters chromosome 4, which can lead to progressive dementia. Huntingtons disease is a dominant genetic condition. This means that if either parent has the condition, they can pass on the gene to their offspring and they will develop the disease.
Symptoms of Huntingtons disease do not usually become evident until a person reaches 3050 years of age. This can make it difficult for doctors to predict or diagnose before a person has children and passes on the gene.
Researchers think that dementia with Lewy bodies or Parkinsons dementia may also have a genetic component. However, they also believe that other factors outside of genetics might play a role in the development of these conditions.
Researchers have identified several risk factors for Alzheimers disease.
- difficulty recognizing people
- frequently misplacing objects and belongings
The aging process might naturally impair a persons memory, but Alzheimers disease leads to more consistent periods of forgetfulness.
Over time, a person with Alzheimers may need an increasing amount of assistance with daily living, such as brushing teeth, getting dressed, and cutting food.
They may also experience agitation, restlessness, personality withdrawals, and speech problems.
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Is Vascular Dementia Hereditary
One of the questions that many people have about vascular dementia has got to be is vascular dementia hereditary?
It develops when there is an inadequate flow of blood to the brain which damages and kills brain cells.
This is normally due to a stroke that suddenly cuts the blood supply to the brain, many mini-strokes, and narrowing of small blood vessels in the brain.
From here, get to learn the role of genes in the human body, as well as essential factors that touch on genetics and vascular dementia below.
Am I At Risk For Alzheimer’s
Whether we have seen early signs in ourselves or not, many of us want to know what our chances of getting this disease may be. Research has shown a number of possible factors that can impact your chances of getting Alzheimer’s disease, although none of these are a cause in and of themselves.
Some ages are more at risk
Old age is one of the most obvious risk factors. The vast majority of people develop the disease after the age of 65, and once you reach 65, your risk of getting Alzheimer’s doubles every five years. But Alzheimer’s doesn’t only affect people over 65 it has been known to affect people half that age, although this is much rarer.
Alzheimer’s is hereditary
A family history will also increase your risk of getting the disease. The risk increases even more if you have multiple family members who have suffered from the disease.
Whilst this may be due to the hereditary genetic factors we will look at in more depth later, there may be other factors at play. These could include environmental factors that impact both yourself and your family.
Gender is another significant risk factor. The first discovery of the disease back in 1906 was in a woman, and about twice as many women as men over 65 have Alzheimer’s. This may be in part to the fact that women have a longer lifespan or may even possibly be linked to menopause.
Genetic factors of Alzheimer’s
Other risk factors
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Is Alzheimers Genetic Or Hereditary Heres What We Know
Alzheimers disease is not completely genetic or hereditary. In very rare cases, a specific gene can directly lead to Alzheimers. In more common cases, having a first-degree family member with Alzheimers increases your risk but does not guarantee you will develop Alzheimers.
Being older than 65 is the most common non-genetic risk factor for developing Alzheimers disease.
Simply put, having a family history of dementia makes it more likely that you will experience dementia. However, people with no family history still develop Alzheimers and people with a robust family history of dementia may not get it.
Alzheimers disease is a neurodegenerative disease and the most common form of dementia, which results in memory impairment and general cognitive decline. About 6 million people have Alzheimers disease in the United States alone, including those who developed it at a younger age.
It is caused by the buildup of beta-amyloid plaque and tau tangles in the brain, destroying brain cells . These buildups may be influenced by many factors:
- Environmental factors
- Other unknown factors
C2N Diagnostics released a simple blood test in 2020 that can measure levels of amyloid plaque particles in your blood plasma, as well as determine if an individual possesses the APOE gene that increases your risk of developing Alzheimers.
Lets dive into everything you need to know about the genetics behind Alzheimers disease.
Researchers Know That Genetics Play A Role In Alzheimers Disease But There Are Also Other Factors That May Cause It To Occur
An Alzheimers disease diagnosis can be overwhelming. In the early stages, mild memory loss and mood swings appear. Later, as the condition progresses, it can severely limit physical and mental capabilities, and eventually lead to death. If you have a history of Alzheimers in your family, heres what you need to know.
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What Are The Chances Of Getting Dementia If A Parent Has It
If a parent has Alzheimers disease, your lifetime risk increases by about 30%. But that may sound scarier than it is.
The lifetime risk of developing Alzheimers for a woman who is 55 years old is 17%. A 30% increased risk raises it to 22%. For men, the lifetime risk rises from 9% to almost 12%.
Those with close family members who developed Alzheimers disease before age 65 are at higher risk. However, early-onset Alzheimers is rare and accounts for a very small percentage of people with the disease.
Is Alzheimers Disease Hereditary
Dr. Larry Lawhorne discusses the hereditary component of Alzheimers disease. Click play to watch the video or read the transcript.
People often ask if they are at risk for Alzheimers if people in their family have the condition. The answer is complicated. There is a genetic component to Alzheimer’s disease and across the globe, there are studies that show that certain chromosomal changes, certain changes in genetic makeup will increase the risk for Alzheimer’s disease and some dementias. In the U.S. and especially in the Miami Valley, we dont really have the strong familial patterns of inheritance for Alzheimer’s disease. But if there is Alzheimer’s disease in the family, you are at increased risk and you should talk with your doctor about how to prepare and plans to put in place.
There is genetic testing that can be done, but it is not helpful in predicting if you will get Alzheimers, and there is no cure. If you’re not going to get this until you’re 70 or 80 years old, you can do a lot of living between now and then.
Information About Genetic Testing
Having a test to look for a faulty gene that causes dementia is only appropriate for a very small number of people. This is because inherited dementia is rare.
If you are worried that you have a strong history family of early-onset Alzheimers disease or frontotemporal dementia, you can speak to your doctor about this.
Not all gene mutations that cause dementia have been identified, meaning that some families may have many affected members, but no mutation can be found. Therefore, a negative test result cannot always rule out a genetic cause of a disease.
If a test is appropriate, your doctor should be able to refer you to a genetic counsellor or specialist. This could be a cognitive neurologist or memory clinic psychiatrist. They will discuss with you the pros and cons of taking a test and what will be involved. They will also tell you where the results will be kept, who they will be shared with, and what the next steps would be. For people found to have a genetic mutation that causes dementia, these discussions will also cover the options available if you are considering starting a family.
To find out more about genetic testing and what support is available you can visit www.raredementiasupport.org or call 020 3325 0828. Leave a message and you will be referred to the most appropriate team member.
What Are The Symptoms Of Early
The symptoms of early-onset Alzheimers disease are much the same as when the disease develops in later life.
Early signs of Alzheimers disease include unexpected memory loss, especially when recalling recent events and the names of familiar people and things.
As the illness progresses, patients develop more severe problems, such as becoming subject to mood swings and being unable to perform complex tasks, like driving.
In the latter stages of Alzheimer’s, they may forget how to do simple things like brushing their hair. It is likely that they will require full-time care towards the end of the illness.
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Genes: A Blueprint For Health And Disease
The genes encoded in our DNA are profoundly involved in many aspects of our health. They act as a sort of blueprint for the construction, operation, and repair of our bodies throughout life. Genes provide instructions for the creation and regulation of our bodys building blocks. We inherit one copy of each gene from each of our parents, which is one reason why every person has a unique appearance and metabolism.
The effects of a gene can be dramatically changed by mutation of even one pair of its molecules. Specific versions of genes, called alleles, are passed down through a familys lineage, potentially creating an entire population of people who share a healthy characteristic such as resistance to cancer a more neutral characteristic such as eye color or a heightened risk for a specific disease such as Alzheimers disease .
Many of us have learned about Mendel, who was an Austrian monk, and the pea plants he bred as he discovered basic principles of genetic inheritance. Just as with Mendels plants, some physical characteristics can be transmitted to our offspring through inheritance of even one version of a gene. Many diseases are inherited this way, too.