Hematologic genetic disorders among Southeast Asian refugees.

Resettlement of Southeast Asian refugees has introduced into the Western Hemisphere many persons of all major ethnic groups from Indochina. They represent several distinctive cultural, genetic, and linguistic groups, and the prevalence of genetic traits among them varies accordingly. We studied 778 Southeast Asian persons resettled in the upper Midwest who belonged to 182 unrelated families from the five major Southeast Asian ethnic groups. High prevalences of hemoglobin E, alpha- and beta-thalassemia disorders, and glucose-6-phosphate dehydrogenase deficiency were found. The prevalences of these four conditions in the refugees are among the highest known in the world. For these groups, iron deficiency is an uncommon cause of microcytosis; instead, the most frequent causes are hemoglobin E and alpha-thalassemia-1. Very serious thalassemic disorders occur with unusually high frequency in the refugees, especially in the Tai-Dam.