Huntington disease: who seeks presymptomatic genetic testing, why and what are the outcomes?

The aims of this study were to: 1) quantify the characteristics of those seeking presymptomatic testing for HD, 2) identify their motivations for testing, 3) quantify the waiting times between the various steps within the testing process, and 4) quantify the outcomes of testing at a large state-wide genetic testing center in Australia. A review of medical charts for all referrals for presymptomatic testing of Huntington disease received over a 4 year period (2006-2010) was undertaken. A total of 152 cases met the study inclusion criteria; the mean age was 39 years, 46 % were male and 61 % underwent genetic testing. Of the males who were tested there was a non-significant trend towards having an affected mother vs father (62 %, p = 0.09), whereas females tested were just as likely to have an affected mother or father. The most frequently cited reasons for seeking testing were "family planning", "plan future", and "need to know". Some 11 % deferred testing following the psychological assessment. Of those at 50 % prior risk, 57.5 % tested positive; this was higher than expected and much higher than reported in other studies. The median times from referral to initial appointment, and then to results was 69 days and 144 days respectively. Overall, this review of medical charts shows the depth of information obtainable from routinely collected data and revealed that a high proportion of patients tested positive for HD at this centre.