Predictive testing for Huntington's disease.

Worldwide, predictive testing for Huntington's disease has become an accepted clinical application that has allowed many individuals from HD-families to proceed with their life without the uncertainty of being at risk. International guidelines have extensively contributed to establishing counselling programmes of high quality, and have served as a model for other genetic disorders. Psychological follow-up studies have increased the insight into the far-reaching impact of test results for all individuals involved. Although the guidelines have served as a useful frame of reference, clinical experience has shown the importance of a case-by-case approach to do justice to the specific needs of the individual test candidate. Issues such as ambiguous test results, lack of awareness in a test candidate of early signs of the disease, non-compliance to the test protocol, or the test candidate's need for information on the relationship between age at onset and CAG-repeat require careful consideration. Receiving a test result is only one of the transition points in the life of an individual at risk; such result needs to be valued from a life-cycle perspective.