Can You Get Alzheimer's if No One in Your Family Has It
Many people wonder if Alzheimer's disease runs in the family. A person'south take chances of having the disease may be higher if he or she has certain genes passed down from a parent. Even so, having a parent with Alzheimer's does non always mean that someone will develop it.
What Are Genes?
Each homo cell contains the instructions a cell needs to do its job. These instructions are made up of DNA (deoxyribonucleic acid), which is packed tightly into structures called chromosomes. Each chromosome has thousands of segments called genes.
Genes are passed downward from a person's biological parents. They acquit information that defines traits such as center color and height. Genes also play a role in keeping the trunk's cells salubrious.
Problems with genes—even minor changes to a gene—can cause diseases like Alzheimer's.
Practise Genes Cause Diseases?
Genetic mutations (permanent alter in 1 or more specific genes) can crusade diseases. If a person inherits a genetic mutation that causes a certain disease, then he or she will usually get
the disease. Sickle cell anemia, cystic fibrosis, and some cases of early-onset Alzheimer's disease are examples of inherited genetic disorders.
Other changes or differences in genes, called genetic variants, may increment or decrease a person's take chances of developing a item affliction. When a genetic variant increases disease hazard but does not directly cause a illness, it is called a genetic chance cistron.
Identifying genetic variants may aid researchers detect the almost constructive means to treat or forbid diseases such as Alzheimer's in an individual. This approach, chosen precision medicine, takes into account individual variability in genes, environment, and lifestyle for each person.
The expression of genes—when they are "switched" on or off—can be affected, positively and negatively, by environmental and lifestyle factors, such as practice, diet, chemicals, or smoking. The field of epigenetics is studying how such factors tin can change a cell'southward Deoxyribonucleic acid in means that affect factor activeness.
Genes and Alzheimer's Disease
In that location are two types of Alzheimer'due south—early-onset and belatedly-onset. Both types accept a genetic component.
Late-Onset Alzheimer's Illness
Almost people with Alzheimer's have the late-onset class of the disease, in which symptoms get apparent in their mid-60s and subsequently.
Researchers take not constitute a specific gene that straight causes tardily-onset Alzheimer'south illness. All the same, having a genetic variant of the apolipoprotein East (APOE) cistron on chromosome 19 does increase a person's risk. The APOE gene is involved in making a protein that helps conduct cholesterol and other types of fat in the bloodstream.
APOE comes in several unlike forms, or alleles. Each person inherits two APOE alleles, 1 from each biological parent.
- APOE ε2 is relatively rare and may provide some protection against the disease. If Alzheimer'southward disease occurs in a person with this allele, it usually develops afterwards in life than it would in someone with the APOE ε4 gene.
- APOE ε3, the virtually common allele, is believed to play a neutral role in the disease—neither decreasing nor increasing risk.
- APOE ε4 increases risk for Alzheimer'south illness and is also associated with an earlier age of disease onset. Having 1 or ii APOE ε4 alleles increases the risk of developing Alzheimer's. About 25 percent of people carry ane copy of APOE ɛ4, and 2 to 3 percent acquit two copies.
APOE ε4 is chosen a risk-factor gene because it increases a person'due south risk of developing the disease. However, inheriting an APOE ε4 allele does not hateful that a person will definitely develop Alzheimer's. Some people with an APOE ε4 allele never get the disease, and others who develop Alzheimer's practice not accept any APOE ε4 alleles.
Recent enquiry indicates that rare forms of the APOE allele may provide protection against Alzheimer's disease. More than studies are needed to make up one's mind how these variations might delay disease onset or lower a person's risk.
Early on-Onset Alzheimer's Disease
Early-onset Alzheimer'south disease is rare, representing less than 10 percent of all people with Alzheimer's. Information technology typically occurs between a person'due south 30s and mid-60s. Some cases are caused by an inherited modify in i of three genes.
The three unmarried-gene mutations associated with early on-onset Alzheimer'southward affliction are:
- Amyloid precursor protein (APP) on chromosome 21
- Presenilin 1 (PSEN1) on chromosome 14
- Presenilin ii (PSEN2) on chromosome 1
Mutations in these genes result in the product of abnormal proteins that are associated with the disease. Each of these mutations plays a role in the breakdown of APP, a poly peptide whose precise function is non yet fully understood. This breakup is office of a process that generates harmful forms of amyloid plaques, a hallmark of Alzheimer's disease.
A child whose biological mother or begetter carries a genetic mutation for ane of these 3 genes has a 50/50 chance of inheriting that mutation. If the mutation is in fact inherited, the child has a very strong probability of developing early-onset Alzheimer's affliction.
For other cases of early on-onset Alzheimer's, research has shown that other genetic components are involved. Studies are ongoing to identify additional genetic run a risk variants.
Having Downwards syndrome increases the take a chance of developing early-onset Alzheimer'south disease. Many people with Down syndrome develop Alzheimer's every bit they get older, with symptoms appearing in their 50s or 60s. Researchers believe this is because people with Down syndrome are born with an actress copy of chromosome 21, which carries the APP cistron.
For more data, see NIA's Early-Onset Alzheimer's Disease: A Resource List.
Genetic Testing for Alzheimer's Disease
A blood test tin can identify which APOE alleles a person has, merely results cannot predict who volition or will not develop Alzheimer's affliction. Currently, APOE testing is used primarily in research settings to identify study participants who may have an increased take a chance of developing Alzheimer's. This knowledge helps scientists look for early brain changes in participants and compare the effectiveness of possible treatments for people with different APOE profiles.
Genetic testing is also used by physicians to aid diagnose early-onset Alzheimer's disease and to test people with a stiff family history of Alzheimer'southward or a related encephalon affliction.
Genetic testing for APOE or other genetic variants cannot determine an individual's likelihood of developing Alzheimer's affliction—just which gamble factor genes a person has. Information technology is unlikely that genetic testing will ever exist able to predict the illness with 100 percent accuracy, researchers believe, because too many other factors may influence its development and progression.
Some people learn their APOE condition through consumer genetic testing or think about getting this kind of test. They may wish to consult a doctor or genetic counselor to ameliorate understand this type of test and their test results. General information nearly genetic testing can be found at:
- Genetic Testing
- What is Direct-to-Consumer Genetic Testing?
- Getting a Genetic Examination
- Genetic Testing FAQ
Alzheimer'due south Genetics Research
Discovering all that nosotros can virtually the office of Alzheimer'south disease genetic take chances and protective factors is an important surface area of research. NIA supports several major genetics inquiry programs. Understanding more than virtually the genetic basis of the disease will help researchers to:
- Reply a number of basic questions—What makes the illness process begin? Why do some people with memory and other thinking issues develop Alzheimer'southward while others exercise not?
- Make up one's mind how genetic risk and protective factors may interact with other genes and lifestyle or environmental factors to affect Alzheimer's risk in any 1 person.
- Identify people who are at high take a chance for developing Alzheimer's so they can benefit from new interventions and treatments as soon equally possible.
- Explicate differences in Alzheimer's disease chance and protection amongst racial groups and sexes.
- Focus on new prevention and treatment approaches
For More than Information About Alzheimer's Disease Genetics
NIA Alzheimer's and related Dementias Educational activity and Referral (ADEAR) Center
800-438-4380
adear@nia.nih.gov
www.nia.nih.gov/alzheimers
The NIA ADEAR Eye offers information and free print publications about Alzheimer's and related dementias for families, caregivers, and health professionals. ADEAR Center staff answer telephone, e-mail, and written requests and make referrals to local and national resources.
National Eye for Biotechnology Data
National Library of Medicine
world wide web.ncbi.nlm.nih.gov
This content is provided by the NIH National Institute on Aging (NIA). NIA scientists and other experts review this content to ensure information technology is accurate and up to date.
Content reviewed: December 24, 2019
Source: https://www.nia.nih.gov/health/alzheimers-disease-genetics-fact-sheet
0 Response to "Can You Get Alzheimer's if No One in Your Family Has It"
Post a Comment