Free fatty acids (FFAs) circulate in blood to provide fuel for metabolism, to serve as substrates for the formation of more complex lipids, and to participate directly in biological signal transduction. Although these are easily detectable in blood, almost all are bound to the blood serum protein albumin. When this happens, FFAs are unable to enter cells, bind to proteins, or serve as substrates for FFA-utilizing enzymes. Only soluble (unbound) FFAs are biologically active, and these soluble monomers represent just a tiny fraction of total FFAs. Because of this, measurements of total FFAs are insensitive to changes in the unbound (active) FFAs.
Dr. Alan Kleinfeld has recently developed a highly sensitive test that is able to measure unbound (and thus active) free fatty acids in the blood. The Center for Neurologic Study is collaborating with Dr. Kleinfeld to measure profiles of unbound free fatty acids in the plasma of amyotrophic lateral sclerosis patients. Initial results have indicated that there are different ratios of the various free fatty acids found in normal patients compared to ALS patients. Although these results need to be confirmed in a larger study, this information could potentially translate into a useful and simple biomarker for a disease which is ordinarily difficult to diagnose.