NTRK1 and Alzheimer disease: Interestingly, purified BFCN from AD patients are characterized by reduced expression of mRNAs encoding the NGF receptor, TRKA, the BDNF receptor, TRKB, and the NT3 receptor, TRKC, as compared to matched control subjects [82], [83], suggesting that increased levels of the neurotrophin ligands for these receptors could functionally offset reductions in their levels and/or activity.