Molecular genetics of neurodegenerative diseases.

Recent progress in human neurogenetics has led to the discovery of new modes of inheritance and disease expression, including 1) stably inherited duplications in Charcot-Marie-Tooth disease type 1a, 2) dynamic mutations in fragile X syndrome and myotonic dystrophy, and 3) identical mutations with different phenotypes in fatal familial insomnia and Creutzfeldt-Jakob disease. The mechanisms by which known mutations of the amyloid precursor protein lead to early-onset Alzheimer's disease remain unexplained, despite hundreds of recent studies of beta-amyloid.