Many of the patients who attend the outpatient mental health clinics already have a long history of psychiatric problems. Their symptoms seem easy to classify, but the misdiagnosis of the patients’ underlying problems can lead to a long series of costly referrals as inpatients or to an ineffective treatment outcome. In this article we focus on three patients whose history and background circumstances had been analysed in detail and who had also been subjected to a genetic analysis. The analyses pointed to an etiology-based diagnosis which had important implications for their future treatment and its outcome.