At this time it is not possible to predict exactly how the function of the HD gene will be determined even after the responsible DNA mutation has been identified. The discovery of a function for a protein or gene of known structure is still a major problem in all species. The ease or difficulty of performing this step in HD will depend in large part on the nature of the HD gene. Characterization of the HD gene and its normal counterpart will certainly provide improved diagnostic capability. It is to be hoped that this information will also lead to effective therapy to ease the suffering of the disease's victims. In the long term, investigations of this type in HD and other neurogenetic disorders will undoubtedly provide new insights into the operation of the human nervous system.