Emotional and functional impact of DNA testing on patients with symptoms of Huntington's disease.

The potential impact of DNA testing on asymptomatic subjects at risk for Huntington's disease (HD) has been addressed by numerous studies, but the effect of revealing the genetic results to patients with a clinically established diagnosis of HD has not been previously evaluated. We studied 36 patients, with equal distribution of men and women, mean age 53.9 (SD 12.3) years (range 25-76) and mean duration of symptoms of 11.2 (SD 7.7) years (range 2-33), whose clinical diagnosis of HD was confirmed by expanded CAG repeats (> 40). Coping strategies and depression levels were assessed before the results of DNA testing were imparted. The assessments were repeated two weeks and three months after the results were explained to the patients and their relatives and were compared to the baseline assessments. This group of HD patients was compared with 10 patients who had similar symptoms but the diagnosis of HD was excluded by normal CAG repeats (< 30). Although some patients with HD expressed a subjective reaction to the positive result (four were "surprised", one was "frustrated", and one "devastated"), there were no differences in any psychological scores including Beck Depression Inventory, functional capacity, symptom interference, independence scale, and other measures of mood and behaviour two weeks and three months later. Similarly, no change was noted in any of these measures in the non-HD group. These results suggest that mood and coping strategies are unaffected by DNA confirmation of diagnosis in symptomatic patients with HD.