Utah has the world's highest incidence of fumarase deficiency, an extremely rare genetic condition which causes severe mental retardation. (religion.blogs.cnn.com)
The mutation, which was identified in three Arab - Israeli sisters with severe mental retardation, is one of only a handful of genes outside the X chromosome that have been linked to intellectual disability. (hhmi.org)
Rubella led to various birth defects including blindness, deafness and severe mental retardation as well as miscarriages and stillbirths across Europe and the U.S. in the 1960s. (wistar.org)