Preparing for predictive testing for hereditary early onset Alzheimer Disease/Cerebral Hemorrhage and pick disease
Tibben A., Niermeijer MF., Stevens M., Van Duijn CM., Van Swieten JC.
Should accurate risk assessment be offered to individuals at-risk for presenile dementia? We addressed this question in our programme on the neurodegenerative diseases presenile Alzheimer Disease/Cerebral Hemorrhage (FAD-CH) (caused by the APP-692 mutation), and Hereditary Pick Disease (HPD) (recently found to be linked to chromosome 17). Follow-up studies on Huntington disease (HD) have provided important lessons for establishing appropriate testing protocols. To study disease-specific characteristics of FAD-CH and HPD, we assessed the coping with being at-risk and the attitude towards predictive testing in a few families that participated in linkage analysis for FAD-CH/HPD. Concise information about the genetic aspects of the disease had induced much uncertainty and fears in those who were not fully knowledgeable about the heredity of the disease. Yet, two-thirds of the studied group would either take or consider taking presymptomatic testing if it was clinically available: more than half expected to have the gene that causes HPD or FAD-CH. The most important reasons for taking the test were : to further basic research, informing children, future planning, and relieving uncertainty. The most commonly cited effect of an unfavorable test result concerned the increasing problems for spouses and children. Most respondents denied that an unfavorable result would have adverse effects on personal mood or their relationship. Individuals at-risk for HPD were significantly more pre-occupied with the occurrence of potential symptoms in themselves, compared with those at-risk for FAD-CH, reflecting the devastating impact that disinhibition in the affected patient has on the family. Given the continuous uptake of testing for HD in the Netherlands (> 100 per year), we expect that individuals at risk for FAD or FLD may utilize testing; the percentage of eventual uptake in FAD-CH/HPD may, as in HD, be modest. The Dutch debate on the individual's duty to disclose genetic information to insurance companies, on exclusion from life insurances of individuals at risk for HD and myotonic dystrophy, and on misuse by employers lead us to emphasize the potential harm of unfavourable test results in the pre-test counselling sessions. In our experience, individuals at-risk tend to underestimate these issues and we advocate that genetic counsellors and psychosocial workers should address these matters, especially in the pre-test counselling sessions. In addition, aftercare in the first and second echelons of health care should comprise proper and consistent information and support about the far-reaching effects of test results.