This evaluation uses Athena’s two key test offerings; the ADmark APOE Genotype Analysis and Interpretation and the ADmark Phospho-Tau/Total Tau/ AB42 Analysis and interpretation (CSF). Both CSF and whole blood are required for the combined testing. Methods used are ELISA (enzyme-linked immunosorbent assay) and RFLP (restriction fragment length polymorphism) to identify and quantify the various biomarkers. The combined testing serves to detect and quantify the APOE e2, e3, and e4 isoforms, as well as the levels of Phospho-Tau, Total Tau, and the AB42 peptide.
Results are reported with an interpretation of the likelihood of AD. Typically, low CSF levels of AB42, along with high Total Tau and Phospho-Tau levels, may reflect an increased likelihood of AD. On the other hand, high levels of AB42, along with low Total and Phospho- Tau levels, may suggest a decreased likelihood of AD. Test results for the ADmark APOE Genotype analysis are also incorporated to determine the possible likelihood of AD. The presence of mainly the APOE e2 isoform suggests a lower likelihood of AD, whereas the presence of mainly the APOE e4 isoform may suggest a higher likelihood of AD.
The ADmark tests are typically ordered not as a routine screening or specific diagnostic tests for AD but used in patients who have some form of dementia or mild cognitive impairment (MCI) along with other tests to aid in the diagnosis of AD. The ADmark evaluation testing is used mainly to (1) improve the diagnostic accuracy of AD and (2) predict conversion from MCI to AD. Athena indicates that the testing can be especially useful in the differential diagnosis of AD where there are atypical features and diagnostic uncertainty. It must be stressed that the ADmark tests should not be routinely performed in all subjects under evaluation for memory loss. Indeed, the use of the ADmark tests, as well as other similar biomarker tests, are currently not recommended for primary care clinical settings but instead for use mainly by specialists in dementia.
