The rare alpha-thalassemia-1 of blacks is a zeta alpha-thalassemia-1 associated with deletion of all alpha- and zeta-globin genes.
Restriction endonuclease mapping with alpha and zeta-globin gene probes showed differences between the alpha-thalassemia-1 (alpha-thal-1) condition in two patients with HbH disease. One patient had the rare black type of alpha-thal-1 together with alpha-thal-2 and HbS heterozygosities. The second patient was a Laotian child with HbE, Hb Constant Spring (alpha-thal-2), and alpha-thal-1 heterozygosities. The diagnoses were based on clinical, hematologic, and biochemical data. Whereas DNA fragments hybridizing to a zeta-probe were obtained from the Laotian type of alpha-thal-1, neither alpha nor zeta-gene fragments could be identified deriving from the black type of alpha-thal-1. Therefore, the black type of alpha-thal-1 is associated with a deletion of the entire zeta 2-psi zeta-psi alpha-alpha 2-alpha 1 gene complex and can be considered a zeta alpha-thal-1. It is likely that homozygosity for such a condition will lead to embryonic wastage, explaining the absence of hydrops fetalis in blacks.
D044383:Black People; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000097:blood; D005260:Female; D005796:Genes; D006580:Genetic Carrier Screening; D005845:Georgia; D005914:Globins / Q000235:genetics*; D006446:Hemoglobin E / Q000235:genetics; D006801:Humans; D007812:Laos / Q000208:ethnology; D008297:Male; D013789:Thalassemia / Q000097:blood / Q000235:genetics*; D001741:Black or African American
D005914:Globins; D004247:DNA; D006446:Hemoglobin E