Familial adenomatous polyposis is a rare, heredity, autosomal-dominant disease caused by a germline mutation. Those who are affected by it experience great relief from sharing information and concern with other patients and families. The strong bond that develops among the members of such groups may explain the patient’s feelings of guilt. The patient did not fulfill DSM-IV criteria for major depression and had no personal or family history of psychiatric illness. Consequently, the patient’s primary care physician and nurses had difficulty explaining his anhedonia. The present case suggests that psychiatric specialists should be involved in the genetic counseling system. Moreover, health care providers should pay attention to potential feelings of guilt in their patients that may be directed toward the family members of individuals participating in a support group who may be receiving the results of genetic tests.