PSEN1 and Myoclonus: Nearly 30 clinical symptoms have been reported to be caused by PSEN1 gene mutations, including forgetfulness and personality changes (13, 14), balance difficulties (15), progressive gait disturbance (16–18), myoclonus (19, 20), extrapyramidal symptoms (21–23), language impairment (24–26), visual structural disorder (16, 27, 28), visual hallucinations (19), vision loss (29), and others.