Polymorphisms in the gene encoding GSK-3β (GSK3B) have been associated with Alzheimer’s disease and frontotemporal dementia [17], [18], and an epistatic interaction between GSK3B and MAPT has been associated with Parkinson’s disease and Alzheimer’s disease [9], [19], [20]. The gene discussed is GSK3B; the disease is early-onset autosomal dominant Alzheimer disease.