The LQT syndrome takes different forms depending on what inherited abnormality of the genetic material (gene) is present. Three forms of the syndrome are clinically important and are described in detail: LQT1, LQT2, and LQT3. Each has different symptoms and is diagnosed and treated differently. For example, in patients with LQT1, exercise and stress trigger cardiac events; in patients with LQT3, rest and sleep are triggers. In patients with LQT2, triggers include both rest and exercise, as well as loud noises, such as being awakened by an alarm clock. Since effective clinical management depends on the type of genetic abnormality, identifying the abnormality benefits the patients. If one family member has the LQT syndrome, all relatives should be tested since sudden death can occur in people with the gene abnormality, even if they don't have the disorder itself.