<qa>  What is the UHDRS?Participants in the study will be evaluated every 9 months for 5 years using the Unified Huntingtons Disease Rating Scale UHDRS--a clinical tool which looks at movement, psychological and behavioral function. The participants will also be asked to complete surveys about their mood, life events, and attitudes or beliefs about being at risk for HD. A blood sample, taken at the beginning of the study, will be confidentially tested to determine if the participant has the abnormal gene for HD. Neither the participant nor any of the PHAROS physicians or coordinators will learn the results of individual gene tests. 