Where Can I Get Genetic Testing for Alzheimer's
Learn about the most mutual genes associated with the early- and late-onset forms of Alzheimer's affliction, and the electric current recommendations for genetic testing.
Can Alzheimer's or other forms of dementia be passed along in the genes nosotros inherit?
This is a very mutual question people ask, and the answer is non the same for all kinds of dementia. In this commodity we volition focus on Alzheimer'southward disease (AD).
Genes: A Cursory Background
The genes inherited from our parents and encoded in our DNA bear on many aspects of our health. They guide the construction, operation, and repair of our bodies throughout life. Our parents accept 2 "alleles" (pronounceduh-leels) or versions of each gene, and we inherit one allele for each gene site from each of our parents. This is why siblings have unique characteristics unless they are identical twins.
Specific alleles that are passed downwardly through a family can affect the likelihood of resisting or developing many diseases. Another way in which alleles may increase the likelihood of developing a disease is the occurrence of spontaneous changes in the construction of an allele, called a mutation. A small chemical change in an allele tin can accept profound effects on a person'southward health. An altered gene may produce an altered protein that creates havoc in the body.
Genes and Alzheimer's Disease
Nearly Cases of Alzheimer's are Not Acquired by a Single Gene
The expert news is that most cases of Alzheimer's disease (Advertising) are not passed along by a single gene. Among the millions of people in the world affected by AD, those known to have adult the disease due to the inheritance of a single gene account for a very small percentage.
The bad news is that fifty-fifty without inheriting one of the genes that are known to transmit Advertisement, the disease is still a significant health take a chance for any older developed.
Early on-Onset Alzheimer's
About one in twenty people with AD have the early-onset class of the disease (EOAD), divers as first before historic period threescore. In only a minority of cases is EOAD attributable to the inheritance of at least one gene allele that is linked with the illness.
At 3 specific gene locations, we know of mutated or duplicated alleles that make the development of AD likely, whether the allele is abnormal through inheritance or mutation. The harmful allele linked with the first of these genes, the factor foramyloidprecursorprotein (APP), increases APP's analogousness for an enzyme that promotes the creation of a toxic protein, called beta amyloid. The other ii important alleles linked with EOAD also increase the product of beta amyloid. They are chosen presenilin one (PSEN1) and presenilin 2 (PSEN2).
Late-Onset Alzheimer'southward
The inheritance of late-onset Alzheimer's disease (LOAD), which is a far more common type of AD, has non been linked with whatsoever single cistron. The risk of developing LOAD, however, is affected by various genetic profiles.
The about studied genetic take a chance factor for LOAD is the apolipoprotein Eastward (APOE) gene, which tin occur in whatever combination of 3 possible alleles: ε2, ε3, and ε4. Each of your parents contributed one of these alleles to your genome.
If you have one ε4 allele, your risk for developing LOAD is increased by a factor of 2 or 3. If you lot have 2 of the ε4 alleles, your chance increased past a factor of 8. On the other paw, the ε2 allele may be protective.
Because the risk for LOAD is affected by multiple genetic and environmental factors, inheritance is non articulate-cut.
Alzheimer's Genetic Testing: Understanding the Pros and Cons
Early-Onset Alzheimer'south
A person with EOAD and a family history that includes iii or more generations of EOAD genetic relatives is a good candidate for testing of PSEN1, PSEN2, and APP and is more likely than not to show a positive result. That data can be useful in confirming an EOAD diagnosis or in providing genetic counseling about the risk of passing forth AD to the next generation. A positive test becomes less likely with a later age of onset and/or a smaller number of affected relatives.
Late-Onset Alzheimer's
With LOAD, the additional question of whether to examination for the APOE allele is raised. Carrying one or two ε4 alleles is an AD risk cistron and also can increase the damaging effect of diverse environmental factors such as smoking or head injury. Yet up to 75 pct of people with 1 ε4 allele remain free of the disease and up to one-half of people with AD exercise non comport the ε4 allele at all.
A positive or negative APOE test could, therefore, provide disruptive or fifty-fifty misleading information to an individual interested in assessing his or her risk of developing or passing forth Advert. APOE testing, therefore, is not generally recommended.
Summary
What do nosotros make of this? Before long, genetic testing'southward office is limited. If the goal of testing is the assessment of risk, there are other less costly, more practical approaches to risk assessment.
While scientists are working to develop claret tests for assessing risk, what we tin do immediately, however, is to monitor measures of wellness such as claret pressure, sleep quality, exercise frequency, glucose metabolism, and lipid profile. These volition provide useful information regarding dementia risk. More importantly, these measures will signal toward lifestyle changes that are risk-reducing!
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- Alzheimer'south Disease Toolkit (Helpful Data to Understand and Manage Alzheimer's Affliction)
- Practiced Information on Alzheimer'south Disease (Articles)
- What Is Your Risk?—Heredity and Late-Onset Alzheimer's Disease (Article)
- Early-Onset Alzheimer's Disease (Article)
- Decreasing Your Hazard of Alzheimer's Affliction (Article)
- Is Alzheimer's a Genetic Illness? (Article)
- Agreement Alzheimer's Disease: It's Not But Forgetfulness (Publication)
Farther reading:
Farrer LA, Brin MF, Elsas L, et al. American College of Medical Genetics/American Society of Man Genetics Working Grouping on APOE and Alzheimer'due south Disease: argument on use of apolipoprotein East testing for Alzheimer'due south disease. JAMA 1995;274:1627-9.
Lleo A, Blesa R, Queralt R, et al. Frequency of mutations in the presenilin and amyloid precursor poly peptide genes in early-onset Alzheimer disease in Kingdom of spain. Arch Neurol 2002:59:1759-63.
Loy CT, Schofield PR, Turner AM, et al. Genetics of dementia. Lancet 2014;383: 828-40.
Pihlstrom 50, Wiethoff S, Houlden H. Chapter 22. Genetics of neurodegenerative diseases: an overview. Handbook of Clinical Neurology. Vol 145. 2018. http://dx.doi.org/ten.1016/B978-0-12-802395-2.00022-v
Verheijen J, Sleegers K. Agreement Alzheimer Disease at the interface betwixt genetics and transcriptomics. Trends in Genetics 2018, https://doi.org/10.1016/j.tig.2018.02.007
Near the author
James Chiliad. Ellison, Medico, MPH
Swank Centre for Memory Care and Geriatric Consultation, ChristianaCare
James Ellison, Doc received his medical degree from UCSF in 1978 and trained in psychiatry at the Massachusetts General Infirmary (1979-1982).
Source: https://www.brightfocus.org/alzheimers/article/genetic-testing-alzheimers-disease
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