At a Glance
Why Get Tested?
To screen for a rare mutation in the PSEN1 gene known to be associated with Early Onset Familial Alzheimer's Disease (EOFAD, also called Alzheimer's disease Type 3 or AD3)
When to Get Tested?
When you are an adult who has symptoms of dementia and a strong family history of Alzheimer's Disease that begins before age 60-65 or if you are an asymptomatic adult with an identified PSEN1 genetic mutation and early onset Alzheimer's Disease in your family line
A blood sample drawn from a vein in your arm
Test Preparation Needed?
The Test Sample
What is being tested?
This test looks for mutations in the PSEN1 gene sequence that has been associated with Early Onset Familial Alzheimer's Disease (EOFAD, also called Alzheimer's Disease Type 3 or AD3). Although most Alzheimer's Disease (AD) cases start after the age of 65 and above, about 5-10% of cases begin in people under 65 years of age. Much of this early onset AD is familial - it runs in family lines and is caused by a genetic mutation. There have been three gene mutations identified so far that are associated with AD3; all are very rare. Of these, PSEN1 is the most common and is thought to cause about 30% to 70% of the cases of AD3. Since PSEN1 is a dominant gene (autosomal dominant), it only takes one mutated copy, inherited from either the mother or father, to cause AD3.
So far, more than 150 mutations of the PSEN1 gene have been identified in a limited number of different family lines worldwide. Why PSEN1 mutations are associated with AD3 is not completely understood. It is thought that the normal role of the PSEN1 gene is to make the protein presenilin 1, a protein used in the development of the brain and spinal cord. It also works with other enzymes to cut certain proteins into smaller pieces (amyloid beta peptide). A mutation of PSEN1 produces an abnormal presenilin 1 protein that no longer functions properly, resulting in a breakdown of this process. This breakdown lends itself to increased production of the longer, stickier configuration of the amyloid beta protein, which is toxic to the nervous system and eventually forms the characteristic amyloid plaques of AD.
The PSEN1 genetic mutation analysis is relatively new and offered by a very limited number of laboratories. The large number of mutations currently known suggests that there may be additional mutations not known; thus this test will not identify every person who has a PSEN1 mutation. The analysis is made easier if a PSEN1 mutation has already been identified in a person's family line.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in your arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
Ask a Laboratory Scientist
This form enables you to ask specific questions about your tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. If your questions are not related to your lab tests, please submit them via our Contact Us form. Thank you.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
(Reviewed 2008 December). PSEN1. Genetics Home Reference [On-line information]. Available online at http://ghr.nlm.nih.gov/gene=psen1 through http://ghr.nlm.nih.gov. Accessed August 2009.
Bird, T. (Revised 2009 April 28). Early-Onset Familial Alzheimer Disease. GeneReviews [On-line information]. Available online at http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene∂=alzheimer-early through http://www.ncbi.nlm.nih.gov. Accessed August 2009.
Anderson, H et. al. (Updated 2009 June 18). Alzheimer Disease. emedicine [On-line information]. Available online at http://emedicine.medscape.com/article/1134817-overview through http://emedicine.medscape.com. Accessed August 2009.
Rogaeva, E. (2009 February 5). The Genetic Profile of Alzheimer's Disease: Updates and Considerations. Medscape Today from Geriatrics & Aging [On-line information]. Available online at http://www.medscape.com/viewarticle/586756 through http://www.medscape.com. Accessed August 2009.
Mayo Clinic Staff (2008 September 17). Alzheimer's: Is it in your genes? MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/alzheimers-genes/AZ00047 through http://www.mayoclinic.com. Accessed August 2009.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Sloane, P. (1998, November 1). Advances in the Treatment of Alzheimer's Disease. American Family Physician by the American Academy of Family Physicians [On-line journal]. Available online at http://www.aafp.org/afp/981101ap/sloane.html through http://www.aafp.org.
Eastman, P. (2002 March). Keeping Alzheimer's at Bay, Early Diagnosis Keeps Patients Functioning Longer. AARP Bulletin Online [On-line serial]. Available online at http://www.aarp.org/bulletin/departments/2002/health/0310_health_1.html through http://www.aarp.org.
McConnell, S. , et. al. Unraveling the Mysteries of Alzheimer's Disease: Exciting New Developments in Research. From panel sponsored by the Alzheimer's Association [On-line information]. Available online at http://www.asaging.org/am/cia2/alzheimer.html through http://www.asaging.org.
Galasko, D., et. al. (1998). High Cerebrospinal Fluid Tau and Low Amyloid b42 Levels in the Clinical Diagnosis of Alzheimer Disease and Relation to Apolipoprotein E Genotype. Arch Neurol [On-line journal], vol (55) pages (937-945). Available online at http://archneur.ama-assn.org/issues/v55n7/abs/noc7433.html through http://archneur.ama-assn.org.
ARF (1996-2002). Standard Medical Workup for Alzheimer's Disease. Alzheimer Research Forum [On-line information]. Available online at http://www.alzforum.org/members/research/treatment_guide/workup.html through http://www.alzforum.org.
Family Caregiver Alliance. Fact Sheet: Alzheimer's Disease [On-line information]. Available online at http://www.caregiver.org/factsheets/diagnoses/alzheimersC.html through http://www.caregiver.org.
Bird, T. (2001 June 22 last update). Alzheimer Overview. GeneReviews [On-line information. Note: It is necessary to register to use GeneReviews, but it is a free site, funded by the NIH]. Available online through http://www.genetests.org.
Gottlieb, F. and Lambert, J. G., [Updated by] (2002, January 2, last update). Alzheimer's Disease. MEDLINEplus [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000760.htm.
Miller, M. (1998 February 18). 26 national Alzheimer's Disease Centers Collaborate on Study of the Utility of Genetic Testing for Alzheimer's. National Institutes of Health News Release [On-line press release]. Available online at http://www.nia.nih.gov/news/pr/1998/02%2D18.htm through http://www.nia.nih.gov.
NIH (2000). Progress report on Alzheimer's disease, taking the next steps. NIH Publication No. 00-4859 [On-line report]. Available online at http://www.alzheimers.org/pubs/prog00.htm#Introduction through http://www.alzheimers.org.
UniSci (2002, April 08). New Approaches Seen For Early Alzheimer's Diagnosis. Daily University Science News [On-line Article]. Review of two studies found in Neuropsychology, Vol 16 (2). Available online at http://unisci.com/stories/20022/0408025.htm through http://unisci.com.
Eldercare (2002 February 28, last update). Is it Alzheimer's ... or Just Forgetfulness? Sponsored by Nebraska's Area Agencies on Aging [On-line information]. Available online at http://nncf.unl.edu/eldercare/info/lifeline/LLforget.html through http://nncf.unl.edu.
Diagnostic Education, Neurological Disorders, Alzheimer's Disease. Athena Diagnostics [On-line information]. Available online at http://www.athenadiagnostics.com/site/content/neuro_alzheim_dis.asp through http://www.athenadiagnostics.com.
NeuroCast. Neuropathology of Alzheimer's Disease. Athena Diagnostics [On-line information]. Available online at http://www.neurocast.com/site/content/sessions_Neuro_Alzheimer's.shtml through http://www.neurocast.com.
NeuroCast. Biochemistry of Alzheimer's Disease. Athena Diagnostics [On-line information]. Available online at http://www.neurocast.com/site/content/sessions_Biochemistry_Alzheimer's.shtml through http://www.neurocast.com.
Hain, T. (2000 February 13). Alzheimer's Disease. Neurology, Northwestern University Medical School [3rd year neurology medical student curriculum material]. Available online at http://www.neuro.nwu.edu/meded/behavioral/alzheimers.html through http://www.neuro.nwu.edu.
Kleiner-Fisman, G., Updated by (2002 January 2, last update). CSF Collection. MEDLINEplus [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003428.htm.