PSEN1 and dementia: When these data is combined with data we have previously published [15, 16, 17] we conclude that among 105 dementia patients, 5.7% are attributable to PSEN1 mutations (6/105), 2.9% (3/105) to C9ORF72 and TREM2 each, and 0.95% (1/105) to MAPT, GRN and NOTCH3 each, while 85.7% (90/105) remain unclear.