General

Synonym/Acronym:
CSF tau protein and β-amyloid-42, AD, APP, PS-1, PS-2, Apo E4.

Common Use:
To assist in diagnosing Alzheimer’s disease and monitoring the effectiveness of therapy.

Specimen:
Cerebrospinal fluid (CSF) (2 mL) collected in a plain plastic conical tube for tau protein and β-amyloid-42; whole blood from one full lavender-top (EDTA) tube for apolipoprotein E4 (ApoE4) genotyping, β-amyloid precursor protein, presenilin 1, and presenilin 2.

Normal Findings:
(Method: Enzyme-linked immunosorbent assay) Simultaneous tau protein and β-amyloid-42 measurements in CSF are used in conjunction with detection of apolipoprotein E4 alleles (restriction fragment length polymorphism) and identification of mutations in the β-amyloid precursor protein (APP), presenilin 1 (PS-1) and presenilin 2 (PS-2) genes (polymerase chain reaction and DNA sequencing) as biochemical and genetic markers of Alzheimer’s disease (AD). Scientific studies indicate that a combination of elevated tau protein and decreased β-amyloid-42 protein levels are consistent with the presence of AD. The testing laboratory should be consulted for interpretation of results.