ETM1: A gene for essential tremor, uncontrollable shaking of the hands and head and sometimes other parts of the body. The ETM1 gene (also called FET1) was mapped in 1997 to chromosome region 3q13 in a study of Icelandic families. EMT1 is responsible for a fine rapid hand tremor; late tremor of arms, tongue, head, legs and trunk; dysarthria; mild rigidity; and stiff gait. The onset of symptoms is about 50 years, later in women than men. The condition is progressive. The intellect is spared.