 In Europe and North America, the incidence of acquired aplastic anemia is rare with two episodes per million people each year, yet in Asia rises with 3.9 to 7.4 episodes per million people each year.While acquired aplastic anemia with an unknown cause is rare, it is commonly permanent and life threatening as half of those with this condition die within the first six months.The prevalence of bone marrow failure is over three times higher in Japan and East Asia than in the United States and Europe.