Interpersonal responses among sibling dyads tested for BRCA1/BRCA2 gene mutations.

OBJECTIVE: The familial context plays an important role in psychosocial responses to genetic testing. The purpose of this study was to compare sibling pairs with different combinations of BRCA1/BRCA2 test results on measures of affect, interpersonal responses, and physiological reactions. DESIGN: Forty-nine sibling dyads with different combinations of BRCA1/BRCA2 test results (i.e., mixed, positive, negative) completed a questionnaire, and 35 of the dyads also participated in a laboratory-based discussion of genetic testing. MAIN OUTCOME MEASURES: The primary outcome variables included participant reports of supportive actions toward their sibling, state anger and anxiety, perceptions of sibling behavior, and electrodermal responses. RESULTS: Compared to positive and negative dyads, mixed pairs reported less friendly general support actions, noted more anger, and perceived their sibling to be less friendly and more dominant during the interactions. In comparisons between same-result (i.e., positive, negative) pairs, positive dyads reported more dominant support behaviors and perceived their sibling to be friendlier during the interactions. CONCLUSION: Data suggest that siblings who have different test results may experience more interpersonal strain than siblings who have the same test result. Future research on genetic testing and family relationships can expand upon these findings.