Mutations in the gene encoding the muscle protein titin is found to cause the heart condition dilated cardiomyopathy (DCM). Scientists have worked out on the variations that are responsible for the disease providing information that will help to screen high risk patients. There are also variations found in many people that are completely benign and do not cause DCM. Mutations in the titin gene make the protein shorter, or truncated. But truncations in the gene are common and around one in 50 people have one and most are not harmful. DCM causes the heart muscle to become thin and weak, often leading to heart failure. Mutations that cause DCM occur at the far end of the gene sequence. Researchers have found that the mutations in healthy individuals tend to occur in parts of the gene that aren't included in the final protein, allowing titin to remain functional. The information on list of mutations in the titin gene, which of these are associated with dilated cardiomyopathy, and which are harmless will be extremely valuable for correct future diagnosis and treatment of DCM.