Discuss PSEN1 results plainly during an Alzheimer's workup: state what the result means, who it affects, and what happens next. Hold the disclosure with counseling, a family member present, and a plan for relatives and protections.
PSEN1 means presenilin-1, a gene in which pathogenic variants cause autosomal-dominant early-onset Alzheimer disease. A positive result is near-deterministic, not a risk factor like APOE. That distinction shapes every conversation that follows.
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
- What does the result actually mean?
- How is PSEN1 different from APOE?
- Who is offered testing during the workup?
- What should relatives hear about inheritance?
- What consent and protections must come before disclosure?
What does the result actually mean?
According to the ACMG/NSGC joint guidelines, pathogenic PSEN1 variants cause autosomal-dominant early-onset Alzheimer disease with onset typically 30-60 years and penetrance described as complete by 60-65 (the joint counseling guidelines). Use clear language: positive means disease is expected, not merely more likely. Name the typical age window and avoid hedging that suggests uncertainty.
A negative result needs equal care. It does not rule out Alzheimer disease when the familial mutation is unknown. Variants of uncertain significance occur, and rare reduced penetrance happens, such as a PSEN1-H163Y carrier symptom-free at 65.
How is PSEN1 different from APOE?
Explain that PSEN1 can cause disease, while APOE e4 is only susceptibility. APOE e4 is neither necessary nor sufficient for Alzheimer disease. Per the ACMG Choosing Wisely statement summarized in the Blue Cross policy summary, clinicians should not order APOE as a predictive Alzheimer test.
This comparison prevents a common error. Families often equate any Alzheimer gene with fate. Correct that view at disclosure, then return to the PSEN1 finding.
Who is offered testing during the workup?
Offer PSEN1/PSEN2/APP testing when dementia looks autosomal-dominant with one or more early-onset cases. The usual triggers are onset generally under 65 or a known familial mutation.
Take a three-generation history before ordering. For symptomatic patients, conduct counseling with a legal guardian or family member present. For cognitively unimpaired at-risk relatives, use separate pre-test and post-test sessions with a support person, modeled on Huntington disease protocol.
What should relatives hear about inheritance?
Tell families each child of a PSEN1 carrier has a 50% chance of inheriting the variant. Describe next options in plain steps, drawing on NCRAD guidance on genetic testing: Keep the focus on choice and timing. Relatives can test now, later, or not at all after counseling.
- cascade testing for at-risk adult relatives
- predictive testing with formal counseling and consent
- reproductive options including prenatal testing and preimplantation genetic testing
What consent and protections must come before disclosure?
Emphasize that predictive testing requires formal genetic counseling and informed consent. Discuss psychological, family, employment, and reproductive implications before any disclosure. Document consent and who may receive results.
Then explain confidentiality limits in concrete terms. According to NHGRI/NIH guidance, U.S. GINA bars use of genetic information in health insurance and employment but does not cover life, disability, or long-term-care insurance (NHGRI guidance on genetic discrimination). Advise families to review those policies before testing.
