ETM2: A gene for essential tremor, uncontrollable shaking of the hands and head and sometimes other parts of the body. The ETM2 gene was mapped to chromosome region 2p25-p22 in a study of a large American family of Czech descent. ETM2 is responsible for essential tremor; postural tremor of arms; and variable tremor of head, legs, trunk, voice, jaw, and facial muscles. The tremor is aggravated by emotions, hunger, fatigue, and temperature extremes.