The tryptic peptide assays of synaptotagmin-1 (215–223 and 238–245) could also each differentiate dementia due to Alzheimer’s disease from controls in both sample sets, with area under the curve of 0.886 (0.755–1.017) (P = 0.0001) and 0.893 (0.770–1.016) (P < 0.0001) (sample set I), respectively, and of 0.815 (0.703–0.926) (P < 0.0001) and 0.795 (0.679–0.912) (P = 0.0001) (sample set II), respectively (Fig. 2b). This evidence concerns the gene SYT1 and Alzheimer disease.