Large sections of the genome that were once referred to as 'junk' DNA have been linked to human heart failure, according to research. So-called junk DNA was long thought to have no important role in heredity or disease because it doesn't code for proteins. But emerging research in recent years has revealed that many of these sections of the genome produce RNA molecules that, despite not being proteins, still have important functions in the body. RNA is a close chemical cousin to DNA.