Experience over fifteen years with a protocol for predictive testing for Huntington disease

To compile a comprehensive profile of the participants who had predictive testing from Huntington disease (HD) between 1994 and 2008 in Montreal, Canada.

This is a retrospective cohort study. The predictive testing protocol consisted of a telephone interview to give information about predictive testing and collect demographic data; a psychological assessment and counseling session; a session focused on medical and family history of HD; a session reserved for genetic counseling; a session where results were given to participants; and a follow-up telephone interview.

A total of 181 applicants requested presymptomatic testing. 135 applicants (77 women and 58 men) completed the protocol and received test results while 40 withdrew. Of the latter, 3 manifested symptoms of the disease and were referred to a neurologist or psychiatrist, and 3 had previously been tested by linkage analysis. Participants usually mentioned more than one reason for requesting predictive testing but the most frequent was to put an end to uncertainty concerning their risk of illness. The proportion of positive and negatives test results was 40% and 54.1% respectively, significantly different from the expected 50% (p<0.01). Prenatal testing was not frequently requested.

All the participants expressed satisfaction regarding their decision to be tested. None to our knowledge had a catastrophic reaction (major depressive disorder or psychiatric hospitalization, declared suicide attempt or suicide). Our study highlights that preparation for receiving test results is a psychologically complex process for which appropriate support in a timely fashion is critical. We feel that a cautious and ethical case by case approach remains essential and that high standards of testing should be maintained because of the far reaching impact of test results.