MG affects 50 to 200 per million people. It is newly diagnosed in three to 30 per million people each year. Diagnosis is becoming more common due to increased awareness. MG most commonly occurs in women under the age of 40 and in men over the age of 60. It is uncommon in children. With treatment, most of those affected lead relatively normal lives and have a normal life expectancy. The word is from the Greek "mys", "muscle" and "astheneia" "weakness", and the Latin "gravis", "serious".