CYP2C19 and CYP2D6 variants affect the occurrence of ADRs in patients treated with selective serotonin reuptake inhibitors (SSRIs) (citalopram, escitalopram, sertraline, fluvoxamine, fluoxetine, and paroxetine), including anxiety, nightmares, and panic attacks associated with CYP2D6 and electrocardiogram (ECG)-prolonged QT associated with CYP2C19 [231]. The gene discussed is CYP2C19; the disease is panic disorder.