The biological significance of a 96 gene expression assay developed to aid the diagnosis of Alzheimer's disease

Summary A new blood test, ADtect®, has been developed to aid in the early detection of Alzheimer’s Disease (AD) [1,2]. The test is based on measuring the expression of selected genes in blood defined as the AD specific gene signature. ADtect® comprises a low density array of 96 selected gene assays on a low density format. The performance of the 96 gene assays together is calculated with an algorithm resulting in a positive or negative test score indicating the presence or absence of AD. In two independent multicenter studies including 204 subjects in total the test is able to discriminate AD subjects from cognitively healthy controls with a 72% overall agreement with clinical diagnosis [2]. The test shows a similar and consistent good performance in both studies [2]. Although the 96 gene expression signature was selected based on predictive value in the algorithm and not on a presumed association with AD pathology, we have previously shown that more than 30 genes are encoding proteins with a biological function associated with AD, brain or neuronal function [2]. We now present a further analysis showing the close connection with known pathways in AD biology for many of the proteins encoded by the genes included in ADtect®.