Prototype Blood-Based Test Aims To Detect Alzheimer's Disease

Further developments are underway to assess if it is feasible to identify, at an early stage, patients suffering from mild cognitive impairment (MCI) who are at risk for Alzheimer-type dementia.

The test is based on hybridizing nucleic acids (RNAs), isolated from a blood sample, on a custom microarray produced by Affymetrix (Santa Clara, CA, USA), which contains sequences identified using ExonHit's (Paris, France) human genome screening technology. The blood test can distinguish patients suffering from AD from those suffering from bipolar disorders, schizophrenia, or depression. The identified sequences (or "signature”) in the blood of patients suffering from Alzheimer's disease can be grouped and are representative of alterations of well-known metabolic functions.

The performances of this test have been improved since March 2007, and it now detects the presence of AD in patients presenting with cognitive disorders, as determined by a Mini Mental State Examination (MMSE) score of less than 20 and a Global Deterioration Scale (GDS) score greater than or equal to four. The test has specificity and a sensitivity of greater than 95% for AD, calculated from a sample of 174 patients.

ExonHit Therapeutics expects to have the test certified and to provide it as a service in its Good Laboratory Practices- (GLP)-compliant laboratories to the pharmaceutical industry by the year 2009.

"Considering our biological signature's properties, we are confident that the test will also be able to screen out patients suffering from other dementias such as frontal lobe dementias, Lewy body dementias, or vascular dementias. This will be validated in mid-2008, after we have compared our signature to the clinical diagnostic criteria for these dementias” declared Laurent Bracco, executive vice president for research at ExonHit Therapeutics.


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