title: alpha thalassemia in black populations.
abstract: The different alpha thalassemia genotypes in American and Jamaican black populations have been defined by hematologic and globin-chain synthesis studies, alpha/beta globin messenger RNA ratios and restriction endonuclease mapping of DNA. The results indicate that the common form of alpha thalassemia in these populations is the deletion type of alpha-thalassemia 2 (- alpha/alpha alpha). The homozygous state (- alpha/alpha- alpha) is expressed at birth by the presence of more than 2--3% hemoglobin Bart's; in adult life it has the same phenotype as the heterozygous state for the deletion form of alpha-thalassemia 1 (--/alpha alpha). The heterozygous state is not always associated with detectable amounts of hemoglobin Bart's at birth or with recognizable hematologic changes in adults.
mesh_terms: D044383:Black People; D005260:Female; D005838:Genotype; D006455:Hemoglobins, Abnormal / Q000235:genetics; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007563:Jamaica; D008297:Male; D009656:North America; D010375:Pedigree; D010641:Phenotype; D013789:Thalassemia / Q000453:epidemiology / Q000235:genetics*
chemical_list: D006455:Hemoglobins, Abnormal