Dementia of the Alzheimer type (AD) is the leading cause of dementias for the elders. It is a progressively neurodegenerative disorder characterized by global cognitive decline. While most of the rare early-onset AD can be explained by mutations in APP gene and presenilin genes,the genetic etiology of the more common late-onset AD is only partly explained by the APOE-epsilon4 genotype. But the APOE-epsilon4 allele is neither necessary nor sufficient to cause disease and it can only account for less than one-half of the genetic variance of AD. Thus, more genes involved in AD are our special attention.