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Huntington's Disease

Onset Of Symptoms For Huntington`s Disease

09/29/2008

Question:

My dad has Huntington`s Disease. If I have it at what age will I start showing symptoms? He was diagnosed in his early 40`s.

Answer:

In response to the question : My dad has Huntington's Disease, if I have it what age will I start to show symptoms? He was diagnosed in his early 40`s. There are multiple factors that affect the age of onset of Huntington's disease symptoms. There is no way to definitely answer this question. One of the things that contributes to determining age of onset is the CAG trinucleotide repeat length of an individual's affected HD gene. There is a general relationship between the age of onset of symptoms of Huntington's disease and the length of the CAG trinucleotide repeats. In general, the higher the repeat size, the earlier the age of disease onset. For instance if an individual's CAG repeat size is 40, age of onset is usually somewhere in the 40's or 50s. If the CAG repeat size is longer and over 50, the age of onset is usually in the teens or 20s. However, in reality there is a wide range of ages over which an individual with a 40 repeat size may present. For instance, symptoms might start at age 25 or not until forty years later at age 65. Other factors may affect age of symptom onset including other genes that an individual might have inherited, for instance those from their other parent. Some of these other genes may delay the age of onset, some might contribute to earlier age of onset. Life style difference, such as how much exercise an individual gets or what foods they eat might also affect the age of disease onset. CAG trinucleotide repeat size is not stable from generation to generation. Though an individual inherits HD from one of their parents, their CAG repeat size may be larger or smaller or the same size as that parents. This is another reason that one can not assume that if one inherited the gene from one's father that they would have the same age of onset of symptoms as their own CAG repeat size may not be the same as their parents. There are several clinical research studies underway, or about to be started, that are looking at agents, supplements and drugs that may be effective at slowing the course of the disease and these may in the future be used to delay onset of disease symptoms.   

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Response by:

Sandra  K Kostyk, MD, PhD Sandra K Kostyk, MD, PhD
Assistant Professor of Neuroscience
Clinical Assistant Professor of Neurology
College of Medicine
The Ohio State University