The familial Alzheimer's genetic panel — a test for APP, PSEN1 and PSEN2 changes — serves as a follow-up, not a stand-alone Alzheimer's diagnosis. Physicians use it inside a wider workup of history, exams, memory tests and brain imaging to clarify suspected inherited disease.
The Alzheimer's Association explains that diagnosis uses medical history, memory tests, physical and neurologic exams, tests and brain imaging (the Alzheimer's Association's guide to medical tests). No single test alone proves the disease. The panel adds genetic evidence to that clinical picture when early-onset inherited disease is suspected.
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 the panel checks
- Who is usually offered testing?
- How results guide diagnosis
- What a known variant means for relatives
- What the panel cannot show
What the panel checks
According to the NCBI Genetic Testing Registry, the hereditary Alzheimer panel tests APP, PSEN1 and PSEN2 by next-generation sequencing with deletion and duplication analysis (the NCBI Genetic Testing Registry entry). It is used for diagnosis, presymptomatic risk assessment and therapeutic management. It focuses on three genes tied to inherited early-onset disease.
ARUP Consult notes that pathogenic APP, PSEN1 and PSEN2 variants are autosomal dominant and explain 60-80% of early-onset familial cases. Autosomal dominant means each child of a variant carrier has a 50% chance to inherit the variant. Finding a causative variant supports a diagnosis of mild cognitive impairment or dementia due to Alzheimer's.
Who is usually offered testing?
A Journal of Neurology review recommends genetic testing for onset under 60 or strong family history with three or more affected relatives (the Journal of Neurology review via PMC). In that group, testing finds APP, PSEN1 or PSEN2 positives in 5-13% of cases. Testing is generally not recommended for late onset after 65 without family history.
Consider testing more strongly when these patterns are present: Bring a family history with ages at onset to the visit. EviCore Lab Management Guidelines state that single-gene testing is rarely useful because familial and nonfamilial disease look alike clinically. The guidelines prefer a three-gene PSEN1, APP and PSEN2 panel with pre- and post-test counseling.
- onset before 60
- three or more affected relatives
- clear early-onset pattern across generations
How results guide diagnosis
A causative APP, PSEN1 or PSEN2 finding supports a diagnosis of mild cognitive impairment or dementia due to Alzheimer's, according to ARUP Consult (ARUP Consult's early-onset Alzheimer guide). The clinician still weighs history, cognitive testing and imaging.
The genetic result can also inform therapeutic management discussions. Pre- and post-test counseling helps families understand inheritance and next steps. A genetics referral can clarify whether additional family testing or follow-up is warranted.
What a known variant means for relatives
ARUP Consult notes that a known familial APP, PSEN1 or PSEN2 variant allows predictive testing of asymptomatic adult relatives. Counseling must cover the 50% inheritance risk. It must also explain that testing cannot predict age at onset or severity.
Testing is offered to adult relatives who want to know their status after counseling. Some relatives use results to plan work, family or care decisions. Others defer testing until family planning or symptoms make results more useful.
What the panel cannot show
Testing.com, citing Mayo Clinic, notes that APOE genotyping alone cannot diagnose Alzheimer's and is only one piece of full clinical evaluation. Major societies do not recommend APOE testing for the general population. The three-gene panel and APOE genotyping answer different questions.
The panel does not explain most late-onset disease without family history. It also cannot predict onset age or severity for a carrier. Ask the clinic about pre-test counseling, family-history review and what follow-up each possible result would trigger.
