Molecular genetics of Alzheimer disease: identification of genes and gene mutations.

Alzheimer disease (AD), the major form of senile dementia, is rapidly becoming a major health problem in developed countries since as populations live longer the number of elderly people continues to grow. Simultaneously, the number of AD cases is increasing since AD is mainly a late-onset disorder and since no effective therapies are available. The primary causes of AD have not yet been elucidated. However, several researchers in different disciplines are actively engaged in AD research with one ultimate goal, i.e. trying to understand the disease pathology. Knowledge of the biochemical basis of the disease may eventually lead to a therapy which either prevents AD or allows AD patients to be treated. One such discipline is molecular genetics. The aim of molecular genetic studies is to identify genes that are either responsible for or contribute to the expression of AD. Once such a gene is identified, studies of its normal and/or abnormal gene product may help us understand the primary disease mechanisms and lead to more effective therapy. Currently, 3 genetic loci have been identified that predispose to AD: AD1 on chromosome 21, AD2 on chromosome 19, and AD3 on chromosome 14. This review aims at summarizing the progresses that have made in identifying genes and gene mutations that predispose to AD.