Alexandra Durr, M.D., Ph.D., delivered this presentation at the sixth World Congress on Huntington's Disease, Rio de Janeiro, Brazil, September 16, 2013. Dr. Durr is a consultant in neurogenetics in the Genetics Department at the University Hospital Salpêtrière in Paris- France. She joined the INSERM (Institut national de la santé et de la recherche médicale) research laboratory in experimental therapy in neurodegenerative disorders in Paris in 1992. After obtaining her medical degree, she earned a Ph.D. in medical genetics in 1998. Her research interest is the phenotypical expression of genetic disorders with a focus on Huntington's disease, cerebellar ataxias, spastic paraplegias and parkinsonian syndromes. Her clinical area of expertise is in rare neurogenetic disorders and presymptomatic and prenatal testing for late, adult-onset neurogenetic disorders. She is a member of the Scientific Advisory Board of INSERM, Scientific Board of the Fondation pour la Recherche Médicale, Scientific Planning Committee of the European Huntington's Disease Network and coordinator of the International Network SPATAX (SPAstic paraplegias and cerebellar ATAXias).