Some patients with the abnormal genes that may cause HCM do not have the characteristic LVH. Approximately 20 - 40% of patients with the genetic abnormality (missense mutation of genes encoding for sarcomeric protein) actually have an enlarged left ventricle. Because of this, researchers believe there may be other factors, along with the genetic abnormality that contribute to the development of HCM. Researchers are interested in learning more about several factors they suspect may play a role in the development of HCM.