title: Frequency of deletional alpha-thalassemia genotypes in a predominantly Asian-American population.
abstract: alpha-Thalassemia is prevalent among Asian-Americans. Most cases involve deletions of one or more alpha-globin genes. Parents with two-gene cis deletions can have offspring with hemoglobin Bart's hydrops fetalis or hemoglobin H disease. The diversity of deletions poses special challenges to laboratories that offer DNA-based testing for alpha-thalassemia. The purpose of this study was to determine both the frequency of alpha-thalassemia genotypes in a predominantly Asian-American population (n = 78) and the mutation detection rate of a comprehensive Southern blot method. The ethnic composition of the study population was similar to the major Asian-American groups that reside in the United States as a whole. Three mutations (the Southeast Asian type, --SEA; -alpha3.7; and the Filipino type, --FIL) accounted for all mutant alleles present in the Asian-American patients tested for reproductive reasons. The relative frequencies of these three mutations were 62%, 27%, and 11%, respectively. The mutation detection rate was 100%. Laboratories that perform DNA-based alpha-thalassemia testing in populations similar to the one residing in Washington State should use a testing system that allows for the unequivocal identification of the haplotypes detected in the study population, namely --SEA, -alpha3.7, and --FIL.
authors.affiliation: Department of Laboratory Medicine, University of Washington, Seattle 98195-7110, USA.
authors.forename: W T
authors.initials: WT
authors.lastname: Hofgärtner
authors.forename: S F
authors.initials: SF
authors.lastname: West Keefe
authors.forename: J F
authors.initials: JF
authors.lastname: Tait
mesh_terms: D000740:Anemia / Q000209:etiology / Q000235:genetics; D001208:Asia / Q000208:ethnology; D001213:Asian / Q000235:genetics*; D015139:Blotting, Southern; D004252:DNA Mutational Analysis; D005260:Female; D017353:Gene Deletion; D005787:Gene Frequency / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008297:Male; D011247:Pregnancy; D014861:Washington; D017085:alpha-Thalassemia / Q000208:ethnology* / Q000235:genetics*