When dementia symptoms progress, ask whether PSEN2 testing fits your family history and what the result would change for care. Also ask what the test can and cannot predict, and what counseling and family testing steps come next. PSEN2 is a rare gene in which harmful variants cause early-onset familial Alzheimer's disease, according to the National Institute on Aging in its Alzheimer's Disease Genetics Fact Sheet.
A child of a carrier parent has a 50/50 chance of inheriting the altered variant, the National Institute on Aging states. Inheritance usually leads to Alzheimer's before age 65, sometimes much earlier. Those two facts shape the first questions to bring to the clinic.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Does your family pattern fit testing?
- What will a result change for care?
- In what order should relatives test?
- What does risk mean for children and siblings?
Does your family pattern fit testing?
Clinicians recommend APP/PSEN1/PSEN2 panel testing for onset before age 60 or strong family history with three or more affected relatives. The University of Pennsylvania Perelman School of Medicine reports a 5-13% yield in early-onset cases on its Advancing Genomic Medicine page.
Ask whether your age at onset and pedigree meet that threshold. Bring dates of symptom onset, diagnoses, and deaths for parents, siblings, aunts, and uncles. Ask if another cause could explain the pattern before pursuing the panel.
What will a result change for care?
PSEN2 Alzheimer's causes progressive dementia that begins with memory loss and confusion. Later stages can add agitation, language loss, and need for total care, with survival often eight to ten years after symptoms, according to the U.S.
National Library of Medicine, MedlinePlus Genetics. Ask what supports match each stage, from safety planning to daily supervision to total care. An important limit frames this talk: PSEN2 status does not usefully predict age of onset, severity, symptom type, or rate of progression, and does not currently change treatment or slow progression, according to Blue Shield of California in Medical Policy 2.04.13.
In what order should relatives test?
Ask about pre- and post-test genetic counseling for yourself and relatives. Counseling covers consent, possible results, privacy, and how results affect family planning and relatives' risk.
Ask whether an affected relative can test first, when possible. The American College of Medical Genetics and National Society of Genetic Counselors advise this order in their June 2011 guidelines to confirm the familial variant and guide others. Useful questions include:.
- Who in the family is the best first person to test.
- How a positive, negative, or uncertain result changes risk for children and siblings.
- What to share with relatives who do not want testing now.
What does risk mean for children and siblings?
PSEN2 follows autosomal-dominant inheritance with about 95% penetrance and typical onset ages 40-75. That differs from complete penetrance for PSEN1 and APP, the same genetics guidelines state.
Ask how to interpret a positive result in light of near-complete but not complete penetrance. Ask when at-risk relatives should seek counseling, even if they feel well. Ask how to document wishes for care, finances, and decision-making while communication remains easier.
