Genetics and molecular biology of Huntington's disease.

In 1993, the genetic abnormality responsible for Huntington's disease was identified as a trinucleotide-repeat expansion in a novel gene. Much has been learned about the molecular genetics of Huntington's disease and the possible effects of the trinucleotide expansion in the development of this disease and other neurological disorders. The Huntington's disease locus is widely expressed throughout the brain and in many non-neural tissues. Current speculation about the pathogenesis of neuronal death concentrates on a 'gain of function' effect in which the abnormal protein has acquired a new and lethal property. Future research will define the normal function of the Huntington's disease locus, test hypotheses regarding the putative gain of function, and explore the factors that determine neuronal susceptibility to the effects of the abnormal allele.