Juvenile Huntington Disease Timing Is Everything

Huntington disease (HD) is a devastating neurodegenerative disorder caused by an abnormal expansion of CAG repeats in the gene encoding the huntingtin protein.1 HD is characterized by progressive striatal atrophy that gives rise to worsening impairments in motor, cognitive, and behavioral domains.2 The age at which these pathologic and clinical changes occur is strongly predicted by the number of CAG repeats one has inherited, but the mean age at clinical onset is generally between the ages of 40 and 50 years old.3 Extensive research has found that striatal atrophy begins approximately 20 years before the onset of motor symptoms in HD. The ability to approximately predict when a patient with HD will begin to have manifestations of their disease has allowed for the planning and conduct of clinical trials. Although no disease-modifying treatments are currently available for HD, there has been an exponential increase in the number of clinical trials that are underway, which has been sparked by building on our understanding of when the disease starts. © American Academy of Neurology.