Yet, many of the known causative mutations reside in proteins that are widely expressed throughout the central nervous system, such as synuclein, LRK2, and Parkin in PD, beta amyloid and presenilin-1 (PS1) in Alzheimer disease, and tau and progranulin in frontotemporal dementia. The gene discussed is PSEN1; the disease is early-onset autosomal dominant Alzheimer disease.