Ethnicity of the participants in this study was by self report. Costa Rican subjects reported 100% bilineal ancestry from Costa Rica, with two subjects reporting partial Nicaraguan ancestry. Guatemalan subjects reported 100% bilineal ancestry from Guatemala, with two of the subjects reporting partial known European ancestry (Belgian and Spanish ancestry). Of the 310 subjects from Mexico who reported on their ancestry, 100% reported bilineal Mexican ancestry, with four reporting partial known ancestry from Western Europe (Spain, France), 3 reporting partial known ancestry from Eastern Europe (Poland), and one reporting partial known ancestry from Puerto Rico. Subjects from the United States reported primarily bilineal Mexican ancestry (94% of subjects), with 5% reporting half Mexican ancestry (one parent) and half non-Hispanic white ancestry (other parent with Anglo-Saxon or Western European ancestry) and 1 person reporting Mexican ancestry from one parent and Puerto Rican ancestry from the other parent. Of the subjects from the United States, 4 reported known partial Native American ancestry, one reported Guatemalan ancestry, and 3 additional subjects with bilineal Mexican ancestry reported partial known European ancestry.
