Because of the usually late onset of Huntington's disease (HD) most sufferers have
reproduced and passed the HD gene to about one half of their offspring before they
themselves develop symptoms of the disease. Genetic counselling of persons at risk of HD
would be greatly facilitated if the gene could be detected presymptomatically. At present,
there is no suitable predictive test for HD, but many approaches currently being investigated
show some promise. These approaches are reviewed and critically evaluated.