Huntington’s disease (HD) is a genetic progressive neuro degenerative disorder that affects movements coordination, behaviour and cognition. It is an autosomal dominant disease, meaning that the children of a person affected by Huntington’s have a 50% probability of inheriting it. It is characterised by a gradual development of involuntary movements (chorea) of the hands, feet, face and trunk; loss of balance; progressive deterioration of cognitive abilities, and behaviour changes. On average, affected people become symptomatic in their early forties, although brain changes begin many years before.
HD is caused by an error in a gene on chromosome 4. This faulty gene, longer than normal, was discovered on 1993 by the international Huntington’s Disease Collaborative Research Group lead by Dr James Gusella. It results in the production of abnormal huntingtin protein, which is toxic for brain cells. Although the length of the faulty gene is partly responsible for the age of disease onset, there are many other factors that seem to hasten or delay the symptoms, and a lot of research on the role of such disease modifiers is currently under way.
The commonly accepted incidence is 7.6 per 100 000 people per year in a population of Northern European ancestry, although recent studies have shown a more likely incidence of 13-17 per 100 000. There is no current data on the incidence in New Zealand. It is estimated that 6% of the general population is carrying a somewhat faulty HD gene, which can potentially expand when passed on to the next generation.
A lot of progress and discoveries have been made since the gene discovery in 1993 and 2015 saw the start of important clinical trials of gene silencing and gene therapy. As one researcher once famously said, “Huntington's disease is the most curable incurable brain disorder”. There is a fantastic research infrastructure worldwide that is committed to finding a cure, and the NZBRI is privileged to be part of this effort.