Patients with Alzheimer’s disease (AD) have two types of abnormal protein buildups: amyloid plaques and neurofibrillary tangles, in addition to the early synaptic dysfunction associated with the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The gene discussed is ACHE; the disease is early-onset autosomal dominant Alzheimer disease.