Uptake and impact of predictive testing - A comparison of breast-ovarian cancer and Huntington's disease

Recent scientific progress has made predictive testing possible for an ever- increasing list of adult-onset genetic disorders. Although uptake of testing for Huntington's disease (HD) has been limited, there has been greater uptake of testing for some hereditary cancers where identification of carrier status may help to plan medical treatment. The genes responsible for some inherited breast and ovarian cancers have recently been identified, and women identified as carriers of BRCA1 mutations can use the information to plan preventative strategies such as screening or prophylactic surgery. However, the efficacy of these preventative measures has not been fully established, and testing has many of the disadvantages of predictive testing for HD because of the potential psychological impact. It is important to know why some people choose predictive tests while others do not, in order to plan appropriate methods of counselling individuals facing this decision. As with HD, several hypothetical surveys suggested a very high level of demand for BRCA1 testing among those at risk, but this has not been born out in practice. In a study of 70 at-risk individuals from 5 families the overall uptake was 52.9%, considerably more than for HD prediction but less than for FAP and VHL where there are greater advantages to knowledge of genetic status. Uptake was higher in women (61.9%) than men (39.3%), higher in those with a greater subjective perception of risk, but lower in those with an affected mother or sister than those where the risk was transmitted by an unaffected father. The most common reasons for testing were to help children and to plan appropriate strategies for the future. Attitudes to testing may be influenced by the greater residual uncertainty after BRCA1 testing, by differences between men and women in attitudes to health-related activities generally and by previous traumatic experiences of the disease in their own families.