HD is a family disease for two reasons. First, it is passed from one generation to the next by the transmission from parent to child of a “mutated” (altered) gene. Each child of an affected parent has a one in two, or 50%, chance of inheriting the gene that causes HD, and is said to be “at risk”. People who carry the gene will eventually develop Huntington’s unless they die of some other cause before the onset of symptoms.
HD occurs in approximately 1 in 10.000 people in most “western” countries. In other countries the prevelance may be much lower.
Males and females have an equal chance of inheriting the gene from an affected parent.
Those who do not inherit the mutated gene will not develop the disease, nor will their children; HD does not “skip a generation”. Genetic testing is available to determine whether or not a person carries the mutated gene for HD.