Risk perception before and after presymptomatic genetic testing for Huntington's disease: Not always what one might expect.

Background In 1983, Huntington's disease (HD) was the first genetic disease mapped using DNA polymorphisms. Shortly thereafter, presymptomatic genetic testing for HD began in the context of two research studies. One of these trials was at the Johns Hopkins University Huntington's Disease Center. Methods As part of the protocol, risk perception (RP) values were collected at 16 time points before and after testing. The current study investigated changes in RP scores before and after genetic testing. Of the 186 participants with pre- and post-testing RP values, 39 also had contemporaneous research clinic notes and recent semi-structured interviews available for analysis. Results The data reveal tremendous diversity in RP. While the RP scores of most individuals change in the way one would expect, 27% of participants demonstrated unexpected changes in RP after disclosure. A significantly higher proportion of individuals who received an expanded repeat result had unexpected changes in RP, compared with those who received normal repeat results. Conclusions The data suggest that individuals' RP is influenced by more than merely the results of genetic testing. This finding is important for genetic counselors and healthcare providers, as it suggests that even comprehensive patient education and disclosure of genetic test results may not ensure that people fully appreciate their disease risk.