Genetic Counseling

School of Health and Human Sciences

Courtney McGuireGenetic Counseling Inter-personal and Intra-personal Individual Variability in Risk Assessment and Prediction of BRCA1 and BRCA2 Mutations
Capstone Project Committee: 
Nancy Callanan, MS, CGC, James Evans, MD, PhD, Catherine Fine, MS, CGC, Claire Healy, MS, CGC, Scott Richter, PhD (Statistical Consultant)
Background Genetic testing for BRCA1 and BRCA2 mutations has been available clinically since 1996 (Iglehart et al, 1998). This is useful in determining if individuals are at an increased risk of developing breast and ovarian cancer. Genetic counselors are often responsible for estimating a client’s risk of carrying a BRCA mutation to determine if genetic testing is recommended. A tool available to help identify individuals who might benefit from testing is BRCAPRO (Euhus, 2004). However, counselors do not always use such computer models; instead they may rely on their own personal experience when assessing a client’s risk. The purpose of this study was to evaluate cancer genetic counselors’ risk estimations of a hypothetical client to determine how counselors’ estimates compare to BRCAPRO, to other counselors, and to themselves over time. Methods At two different time points, cancer genetic counselors completed the study survey, which consisted of ten pedigrees comparable to those seen in a cancer genetics clinic. The counselors evaluated the pedigrees and assigned a risk estimate to the indicated proband. These risk estimates were analyzed to determine if there was significant variability. Results The risk values generated by participants showed considerable inter-personal variability. When compared to BRCAPRO, counselors’ risk estimates were significantly different (p<0.05) in eleven out of the thirteen risk assessments. However, the average of the counselors’ risk estimates between the two time points was not significantly different. Conclusions The results of the study indicate that there is significant inter-personal variability among counselors’ risk estimates when presented with the same pedigree. There is not significant intra-personal variability over time. In the majority of cases counselors’ risk estimates varied significantly from the risk generated by BRCAPRO. In some instances the counselors’ risk estimates may be a more appropriate reflection of the client’s true risk given the limitations of BRCAPO.
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