Gene Therapy, Genetic Testing, and Uses of Genetic Information - Case J2

Helen Freitag is a physician and geneticist who has conducted groundbreaking research on the genetic basis for Huntington's disease, a debilitating, incurable disease that slowly robs its victims of mental and physical functioning and is ultimately fatal. Onset typically occurs in the late 40's to early 50's and the disease may progress in excruciating fashion for up to 15 years. The ultimate goal of Dr. Freitag's research is to find the sequence defect that causes the disease so that some mechanism of repairing the defect can be developed and implemented through gene therapy. In the meantime, Dr. Freitag's task is to locate the gene, which is done by identifying a genetic marker -- a sequence of genes that are not responsible for the disease itself, but that are detectable and inherited in very close correlation with the defective genes.

Dr. Freitag believes she has uncovered a highly predictive marker and wishes to conduct a special project in which she would characterize the inheritance of the marker in families with a history of Huntington's disease. This project will confirm the predictive value of the marker.


  1. Given the moderate uncertainty with regard to the predictive value of the marker, what should Dr. Freitag tell her research subjects when she finds that they have the genetic marker? What if the marker were predictive in every case? How might she involve patients in this decision and what issues might they consider?
  2. Assume this is not a project of research, but a diagnostic procedure in which the predictive value of the marker were certain. If you knew you had a 50% probability of inheriting the defective gene, would you choose to take this test? Why or why not?


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