Our human Amyloid beta x-40 (hAβ40) and x-42 (hAβ42) ELISA test kits represent a new and unique generation of Alzheimer’s disease diagnostics and are setting new standards for the industry. First generation products based on the measurement of levels of tau protein and / or the hAβ42 peptide have shown significant drawbacks and problems. For example, the measurement of hAβ42 levels alone has been shown to produce false positive results because total Aβ42 concentrations vary among humans depending on their age, genetic profile etc.
In order to eliminate the influence of such factors, The Genetics Company’s ELISA kits enable the calculation of the ratio of the respective concentrations of the two Amyloid beta peptide variants, hAβ42 and hAβ40. Since hAβ42 is the main plaque-building and thus Alzheimer’s disease-relevant peptide, first generation Alzheimer’s disease diagnostics have focused on the measurement of the levels of this variant. The non-pathogenic peptide hAβ40 had, however, hitherto largely been neglected. The Genetics Company has validated the measurement of hAβ40 levels as an important reference marker for the standardization of the test results and the normalization of hAβ42 concentrations.
The Genetics Company has developed a worldwide unique set of monoclonal antibodies, which is highly selective and specifically discriminates between hAβ40 and hAβ42. By measuring and dividing the hAβ42 concentration [pg/ml] by the hAβ40 concentration [pg/ml], the dimension-less parameter "normalized Aβ-ratio" is calculated according to the formula described below. A ratio below 1.0 indicates that the patient has a very high risk of developing, or is already suffering from, Alzheimer’s disease.
For further information about the Aβ42/40-Ratio please download the below overview on clinical studies or contact us alternatively.
As mentioned above, the "normalized Aβ-ratio" has already enabled early, efficient and reliable identification of patients at risk from Alzheimer’s in a variety of clinical trials.
The above graph displays the results of a clinical study in which patients were diagnosed with Alzheimer’s disease according to a neurological assay (Minimental State Examination) in comparison to the profiling of these patients based on The Genetics Company’s Aβ42/40 ratio test. Patients analyzed were suffering from Alzheimer’s disease, non-Alzheimer’s disease dementia and other CNS diseases unrelated to dementia. The diagnostic sensitivity (share of positives) and specificity (share of negatives) was calculated with regard to different cutoff values. At a cutoff value of 1, the Aβ42/40 ratio correctly identifies 96.3% of all Alzheimer’s disease patients and selectively distinguishes 88.9% of all Alzheimer’s disease patients from non-Alzheimer’s disease patients (see table below). These values easily fulfill the recommendations for specificity and selectivity expected of a biomarker for Alzheimer’s disease (Consensus Report of the Working Group on: "Molecular and Biochemical Markers of Alzheimer’s Disease" PubMed). The results of this study are particularly interesting because the Aβ42/40 ratio was able to identify Alzheimer’s disease patients at early stages whereas Minimental State Examination yielded unreliable diagnostic information (personal communication).
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Ida N, Hartmann T, Pantel J, Schroder J, Zerfass R, Forstl H, Sandbrink R, Masters CL, Beyreuther K
Analysis of Heterogenous βA4 Peptides in Human Cerebrospinal Fluid and blood by a Newly Developed Sensitive Western Blot Assay
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For more references regarding the Aβ-Ratio as well as our research and diagnostic products please see the References section in the ELISA Kits or Antibodies menu.
