There are no indications that E.T. is hereditary, research in E.T. is much less than other more common deseases. ET is most frequently diagnosed in older individuals (median age of about 60 years at diagnosis), and the gender distribution is about equal between men and women. There is a less common subset of younger patients with apparently typical ET, the majority of whom are women. ET is rarely seen in children. No environmental risk factors for the disease have been identified.