Who Is More Likely to Get Huntington’s Disease?
HD is a hereditary condition. It is passed from parent to child through a mutation (change) in a specific gene. Each child who has an HD parent has a 50% chance of inheriting the copy of chromosome 4 with the HD mutation. A child cannot contract the disease or transmit it on to future generations if they do not inherit the HD mutation. HD is referred to as sporadic when it develops randomly.
A huntingtin protein gene mutation is the root cause of HD. The flaw makes the cytosine, adenine, and guanine (CAG) DNA building components repeat many more times than they should.
Most people have smaller than 27 CAG repeats in their HD gene, so they are not at risk for the disease. People who have CAG repeats in the middle range (27 to 35) are not likely to develop the disease, but they could still pass it on to future generations. People with HD are likely to have 36 or more CAG repeats.
A parent with HD has a 50% chance of passing the HD gene to each of their children. Without the HD gene, a kid will not have the condition and, in most cases, won’t be able to pass it on to their offspring or other future generations.