MacDonald drew a diagram of the disease (please see Figure AH-2: “HD pathogenesis and progression” below), its original CAG repeat mutation, and the age of onset. She and Gusella are currently looking for genes that interact with the original mutation. They conceptualize the disease in the human body as a series of steps in time from the HD CAG mutation to the onset of nerve cell death, to clinical symptoms and then the progression of the symptoms with factors that can effect each step (modifiers) determining the rapidity of each step and the age of onset of symptoms. Their labs are working to produce information about the genetic factors that determine the age of onset in the HD-MAPS (HD Modifiers in Age of Onset in Pairs of Siblings) study, coordinated by Dr. Richard H. Myers of the Boston University School of Medicine. By understanding the biological modifiers of onset, researchers may be able to develop methods to delay the onset of HD. Similarly, in the Huntington’s Disease PREDICT-HD (Neurobiological Predictors of Huntington’s Disease) study, conducted by Dr. Jane S. Paulsen of the University of Iowa, individuals who are known to have the gene expansion for HD are continually being recruited for a brief study examining changes in the DNA (genetic factors) that influence the age at onset of the disease.
Figure AH-2: A conceptual diagram of HD
Last Modified: 05/22/2009
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