Review: Huntington Disease in County Donegal

The paper reviewed here is ‘Huntington Disease In County Donegal: Epidemiological Trends over Four Decades’ by Morrison and Nevin from 1993 and freely available here.

In the introduction, the authors cite work (by one of the authors) estimating the prevalence of Huntington’s Disease in Northern Ireland at 6.3/100,000 (in publications/dissertations dated 1992-1993). Cases were identified by contacting neurologists, GP’s and psychiatrists in county Donegal to obtain contact details of people with identified Huntington’s Disease. These people were then contacted and further afflicted family members were identified as well as those at risk. If we assume that families of people with Huntington’s Disease have at least one member in contact with services then it seems that this is a very effective method for identifying prevalence in the population – it would seem that this would capture most of the people in the county – except for those not registered with health services or those that have migrated in or out of the county or those who have inherited the condition but have not yet expressed it nor are considered at risk. The former groups would most likely represent a small percentage of the population whilst the number of those with the condition who are not considered at risk would depend upon the screening methodology which is not described.

From this information, the researchers were able to produce a value for the number of cases in different time periods and by using this in conjunction with census data were able to estimate prevalence rates over these periods. For 1991 they estimated the prevalence as 1.6 cases per 100,000 of the population. For previous years, the highest estimated prevalence was 4.6 cases per 100,000 in 1926 and the authors suggest this may actually be an underestimate. Between 1926 and 1991 the population size was actually highest in the earliest period, which was attributed to migration out of county Donegal where the main industry had been farming. It was suggested that the prevalence of Huntington’s Disease had decreased because of this migration and that some of the descendants of probands had been traced to the United Kingdom. They also list identified prevalences in other areas including the Moray Firth in Scotland which has an estimated prevalence 560 cases per 100,000 of the population from a 1962 paper (Another area was Lake Maracaibo which has been described as having the highest estimated prevalence in the world of 700 case per 100,000 of the population – again in this area fishing is the main industry (it is tempting to ask if sustainable fishing might itself influence migration rates in a population)


This is a finding with results that are of potential importance in informing local health strategies.

STT3 (Findings could influence population level strategies including allocation of relevant resources)


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The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.


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