Touching Lives - February 2007
No longer a game of chance
Huntington’s disease (HD) is an incurable brain condition, which progressively affects a person’s ability to walk, talk, think and reason. Some who carry the faulty gene develop symptoms in their thirties, others in their fifties, and some — a lucky few — do not suffer the effects of the disease at all. The reasons for these differences are poorly understood.
Two years ago Touching Lives reported on research investigating the geneticfaults which cause HD, and we can now provide an update.
In simple terms, the Huntington’s gene is ‘bigger’ than normal because part of the genetic sequence is repeated several times. Scientists have discovered that if this sequence is repeated more than 40 times the gene is unequivocally abnormal, and the person will develop HD at some point in the future.
But there is a group of people who have between 36 and 39 repeats who may, or may not, develop the condition. This research concentrated on people who fall into this grey area, developing methods for predicting whether they are likely to develop the disease, and, if so, at what age symptoms may appear.
Thanks to funding of almost £11,000 from Action Medical Research, and generously supported by charitable trusts including Westfield Health, Dr Oliver Quarrell and his team at Sheffield Children’s Hospital, was able to collect and analyse DNA samples from patients from all over the world who have between 36 and 39 repeats in the Huntington’s gene. The data they gathered showed that these people have a 40 per cent chance of not developing HD by the age of 65, and a 30 per cent chance of still being asymptomatic at 75.
These important findings will help to determine the probability of a person developing HD by a specific age, allowing doctors to provide patients with clearer information about how they may be affected in the future.