Essential Tremor Definition
Uncontrollable shaking (tremor) of the hands and head and sometimes other parts of the body. Essential tremor is the most common of all movement disorders and is estimated to affect 3 to 4 million people in the US. In more than half of cases, essential tremor is inherited in an autosomal dominant manner. In 1997, the ETM1 gene (also called FET1) was mapped to chromosome 3 in a study of Icelandic families while another gene, called ETM2, was mapped to chromosome 2 in a large American family of Czech descent. That two genes for essential tremor have been found on two different chromosomes demonstrates that mutations in various genes may lead to essential tremor. The mainstays of treatment are drugs such as propranolol and primidone.