Dystonia in Amish-Mennonite and Mennonite Families

Because of common ancestral founder mutations, genetic diseases are frequent in the Mennonites and Amish-Mennonites. However, unlike many genetic disorders that are increased in ethnic groups, dystonia in the Mennonites and Amish-Mennonites is typically associated with an autosomal dominant disorder, DYT6. DYT6 was first mapped, and then identified in three Amish-Mennonite families. Nonetheless, there is a heterogeneous etiology for dystonia in the Amish-Mennonites: the relative contribution of DYT6 is not known, other presumed dominant but not yet identified dystonia genes contribute, as do recessive metabolic disorders. The approach to discerning the etiology of dystonia in these groups is therefore similar to that of other forms of dystonia and relies heavily on careful evaluation of the history, examination, and clinical phenotype. This section will discuss the geographic origins of Amish-Mennonite and Mennonite groups as a window to understanding founder mutations and focus on DYT6 dystonia, an autosomal dominant mixed phenotype primary dystonia. It will also address other etiologies for primary dystonia in the Amish-Mennonites including DYT1, unknown primary etiologies, as well as etiologies for secondary dystonia which may be increased in Mennonites and Amish-Mennonites due to the founder effects in these groups.