The search is on to find "biomarkers" to diagnose neurodegenerative disorders. This interesting article discusses analyzing heart-type fatty acid-binding protein (H-FABP) and tau protein in CSF (cerebrospinal fluid) and serum to differentiate between DLB and AD. (DLB is a synucleinopathy and AD is a tauopathy.)
Robin


Neuro-degenerative Diseases. 2007 Jul 6;4(5):366-375 [Epub ahead of print]

Serum Heart-Type Fatty Acid-Binding Protein and Cerebrospinal Fluid Tau: Marker Candidates for Dementia with Lewy Bodies.

Mollenhauer B, Steinacker P, Bahn E, Bibl M, Brechlin P, Schlossmacher MG, Locascio JJ, Wiltfang J, Kretzschmar HA, Poser S, Trenkwalder C, Otto M.
Center for Neurologic Diseases, Brigham and Women’s Hospital, Boston, Mass., USA.

Background: The measurement of biomarkers in cerebrospinal fluid (CSF) has gained increasing acceptance in establishing the diagnosis of some neurodegenerative diseases. Heart-type fatty acid-binding protein (H-FABP) was recently discovered in CSF and serum of patients with neurodegenerative diseases.

Objective: We investigated H-FABP in CSF and serum alone and in combination with CSF tau protein to evaluate these as potential biomarkers for the differentiation between dementia with Lewy bodies (DLB) and Alzheimer's disease (AD).

Methods: We established H-FABP and tau protein values in a set of 144 persons with DLB (n = 33), Parkinson disease with dementia (PDD; n = 25), AD (n = 35) and nondemented neurological controls (NNC; n = 51). Additionally, serum H-FABP levels were analyzed in idiopathic Parkinson disease patients without evidence of cognitive decline (n = 45) using commercially available enzyme-linked immunosorbent assays. We calculated absolute values of H-FABP and tau protein in CSF and serum and established relative ratios between the two to obtain the best possible match for the clinical working diagnosis.

Results: Serum H-FABP levels were elevated in DLB and PDD patients compared with NNC and AD subjects. To better discriminate between DLB and AD, we calculated the ratio of serum H-FABP to CSF tau protein levels. At the arbitrary chosen cutoff ratio >/=8 this quotient reached a sensitivity of 91% and a specificity of 66%.

Conclusion: Our results suggest that the measurement of CSF tau protein, together with H-FABP quantification in serum and CSF, and the ratio of serum H-FABP to CSF tau protein represent marker candidates for the differentiation between AD and DLB.

PubMed ID#: 17622779 (see pubmed.gov)

Not bad sensitivity/specificity number; the great news is that there are commercial assays on the market for FABP that are, I believe, approaching FDA clearance for diagnostic use - I may be wrong, but I think that all of the FABP assays out there right now are research-only.

My quick look at ARUP, my lab of choice for wonky specialty assays, does not show them offerring it, and lord knows, if there's a billing code for it, ARUP has it. (You should see what they get for a CoQ10 level!)

This could be game changing - CSF collection, while slightly unpleasant, is routine in some settings, and a candidate marker with that kind of numbers out of the box is pretty freakin' impressive.

Eric