Familial context of genetic testing for cancer susceptibility: moderating effect of siblings' test results on psychological distress one to two weeks after BRCA1 mutation testing.

OBJECTIVES To determine whether psychological distress differs among individuals tested for a BRCA1 mutation and is moderated by the pattern of their siblings' test results. MATERIALS AND METHODS Participants in this study are members of a large kindred identified with a BRCA1 mutation. Subjects included 87 males and 125 females who completed a baseline interview, were tested for a BRCA1 gene mutation, received their results in person from a genetic counselor, completed a follow-up interview 1-2 weeks after the receipt of their test results, and had complete data on all variables used in the analysis. The main outcome of the study was psychological distress as measured by the Impact of Event Scale during the 1-2 week follow-up interview. Data were analyzed based on multiple regression. RESULTS Male carriers, relative to noncarriers, experienced significantly more distress if they were the first tested than when all of their tested siblings were already known to be negative. Noncarrier males whose siblings all tested positive also encountered significant test-related distress. The largest adverse psychological consequences for female carriers, relative to noncarriers, were for those who were tested first and those whose tested siblings were noncarriers. CONCLUSIONS The familial context in which genetic testing is conducted may be important for understanding how individuals react to their own test results.