Once recruitment, subject consent, and competency to participate have been achieved, the diagnosis will be assessed through clinical interview, aided by medical records, when available. A complete medication history will be taken including all known medications, their doses, and duration of use, to determine exposure to antidepressants metabolized by CYP450 2D6 and 2C19 and absence of concomitant CYP 2D6 and 2C19 inhibitors. A list of the antidepressants metabolized by CYP450 2D6 and 2C19 and their inhibitors is attached. If exposure is confirmed, each subject will be interviewed using the English version of UKU (Udvalg for Kliniske Undersogelser) Rating Scale14 to retrospectively assess their side effects from medications metabolized by CYP 2D6 and 2C19 enzymes. We will use the modules 1, 3 and 4 of the UKU, for "psychic", "autonomic" and respectively "other" side effects. Only patients who had marked side effects from one medication or either moderate or marked side effects from two medications metabolized by CYP 2D6 and 2C19 enzymes, according with UKU, will be included in the TREATMENT-INTOLERANT group. Subjects who have none or mild adverse effects, will be included in the CONTROL group. The subject interview is expected to last approximately ninety minutes and will be conducted by a sub investigator (Adriana Foster, MD).