Importantly, neuron loss in AD appears not to be the reason for the observed loss in NF-L; a classic study of 22 control, non-AD dementia and AD brains indicated that the significant decrease of NF-L mRNA in AD neocortex could not be adequately accounted for by a non-specific effect of brain damage, by neuron cell loss or by neurons with neurofibrillary degeneration (McLachlan et al., 1988; Julien and Mushynski, 1998; Ginsberg et al., 2000; Zhao et al., 2017a,b). The gene discussed is NEFL; the disease is Alzheimer disease.