Inherited information
Genetic testing
Could inherited biology help explain a personal or family pattern?
Two different kinds of genetic information
Genetic testing can refer to two very different questions. Some tests look for rare genetic variants that can directly cause an inherited neurologic disease. Others look for common variants, such as APOE, that change risk but do not determine a person's future. Those results should not be interpreted in the same way.
The process usually begins with a careful personal and family history. A clinician or genetic counselor can then help decide whether testing is likely to be informative, which test fits the question, and what a positive, negative, or uncertain result could mean. The laboratory test itself usually uses blood or saliva. The conversation before and after testing is an important part of the test.
What a result can and cannot tell us
Rare variants in genes such as APP, PSEN1, and PSEN2 can cause inherited forms of Alzheimer's disease. Other genes can cause inherited forms of frontotemporal degeneration and related conditions. When a disease-causing variant is found, the result can help explain a family pattern and may have meaning for biological relatives.
APOE is different. It can increase or decrease the probability of Alzheimer's disease, but it is not a diagnosis and it cannot tell us whether, or when, a person will develop symptoms. A negative gene panel does not rule out a genetic contribution, and a variant of uncertain significance is not a diagnosis.
Testing can also uncover information a person did not expect. Results may have emotional, family, privacy, and insurance implications. These issues are worth discussing before a sample is sent, not after the result arrives.
From Dr. Anil
Why I may recommend it
Genetic testing is most informative when symptoms begin unusually early, when several relatives have had a similar condition, or when a disease-causing variant is already known in the family. APOE testing may also be discussed when certain anti-amyloid treatments are being considered because it can contribute to treatment-risk counseling.
The goal is not to order the largest panel available. It is to choose the test that can answer the family's actual question and to interpret the result with the clinical history.
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Last reviewed September 2026 by Anil R. Wadhwani, MD, PhD.