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Lab test

Quest AD-Detect® Apolipoprotein E (ApoE) Isoform, Plasma Test

This test determines which ApoE genotype — a combination of E2, E3 and E4 alleles — a person carries, using a plasma sample analyzed by liquid chromatography/mass spectrometry.

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About this test

ApoE is a well-studied genetic risk factor for late-onset Alzheimer's disease. The three ApoE isoforms differ by two amino acids that affect the protein's structure and how it interacts with lipids and beta-amyloid; this test uses LC/MS analysis of plasma to distinguish which isoforms a person carries.

Quest notes that the E4 allele is more common among people with Alzheimer's disease than in the general population, and that the number of E4 alleles a person carries is associated with increased disease risk and an earlier average age of onset. Quest also notes that ApoE and beta-amyloid can co-localize in the brain, and that circulating plasma ApoE levels have recently been studied as a potential biomarker.

Test details

CollectionQuest patient service center

Quest resources

Additional details

What this test looks at

The test reports which combination of E2, E3 and E4 alleles a person carries — their ApoE genotype — determined from a plasma sample using liquid chromatography/mass spectrometry.

This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does this test measure?

It determines which ApoE genotype — a combination of E2, E3 and E4 alleles — a person carries, from a plasma sample.

How is the sample collected?

The test uses a plasma sample from a routine blood draw.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

Does carrying the E4 allele mean I will develop Alzheimer's disease?

No. Quest describes the E4 allele as associated with increased risk and an earlier average age of onset, not as a determination that the disease will occur.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.