Non-participation in predictive testing for Huntington's disease: individual decision-making, personality and avoidant behaviour in the family.

Subjective risk perception, perceived impact of Huntington's disease (HD), perceived benefits and barriers of predictive testing and personality characteristics of persons withdrawing from the predictive test programme for HD and of siblings of test applicants were studied in a mailed survey. The belief that important decisions do not need to depend on a test result and the anticipated inability to cope with a bad result played an important role in the decision not to be tested. Nevertheless half of the group who ever considered testing, still planned to undergo a test in the future. A comparison of tested and untested persons revealed that the first group is more likely to overestimate the risk than the second group, but that both groups did not significantly differ from each other regarding anxiety, ego strength and coping strategies. An intrafamilial analysis of tested and untested siblings confirmed these findings. The problems during data collection and the reasons for the dropout are an illustration of the avoidant behaviour regarding HD and the predictive test in many individuals and families.