Controversies and pitfalls in diagnosing Huntington's Disease

Huntington's disease is an inherited disorder characterised by involuntary movements, as well as psychiatric and cognitive disorders, that occur on average between the ages of 30 and 50. The diagnosis is made on the basis of the motor characteristics of the disease. The diagnostic confidence level, or the extent to which the researcher thinks that the characteristics fit the disease, is used for this. This research shows that this scale is not a reliable instrument for determining the onset of the disease. A small group develops the disease during childhood (paediatric Huntington's disease). In these children, it often takes a long time before the diagnosis is made. Interviews with parents show that although they believe that an earlier diagnosis would have been beneficial for their children, they themselves benefited from postponing the diagnosis due to grief at the loss of, or great concern for, their partner with Huntington's disease. Another group becomes ill at an older age (>60 years; late-onset Huntington's disease). These patients often experience balance problems from the outset of the disease and it is often not clear to them that Huntington's disease runs in the family. This makes it more difficult to diagnose the disease in this group. Huntington's disease is caused by an abnormal elongation in the Huntingtin gene. Repeats between normal and abnormal elongations are called intermediate. There is doubt about whether these people can develop disease symptoms. This dissertation does not find sufficient evidence to substantiate this. People who are at-risk for the disease can have their DNA tested through predictive research. Usually such a person is only seen by a clinical geneticist, but sometimes also by a neurologist. This dissertation shows that patients appreciate being seen also by a neurologist, regardless of the results.