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  • Title: Asymptomatic homozygous deletional beta(0)-thalassemia in an African individual.
    Author: Faustino P, Reis AB, Feliciano H, Ferrão L, Pereira P, Picanço I, Miranda A, Seixas T, Romão L, Júnior EC, Lavinha J.
    Journal: Am J Hematol; 2002 Jul; 70(3):232-6. PubMed ID: 12111769.
    Abstract:
    Homozygosity or compound heterozygosity for beta(0)-thalassemia mutations most commonly results in a transfusion-dependent thalassemia major phenotype. In this report, we describe a 55-year-old male, from Guinea-Bissau, that had been asymptomatic and never transfused until being admitted to hospital with anemia, fever, splenomegaly, and asthenia. Following hospital admission, HIV-2 and Mycobacterium tuberculosis infections were diagnosed, and biochemical and molecular studies revealed homozygosity for beta(0)-thalassemia. At the molecular level, this is the first description of homozygosity for the beta(0)-Black 1,393-bp deletion. In this case, the complete absence of beta-globin gene expression seems to be compensated by an unusually high fetal globin gene expression (Hb F 96%). Beta-globin haplotyping results were compatible with the propositus being homozygous for the Black 2 haplotype and for the absence of the XmnI polymorphism at -158 of (G)gamma-globin gene (-/-). Co-inheritance of genetic factors usually associated with high Hb F levels was not detected. Otherwise, the propositus is a heterozygote for the alpha-globin gene 3.7-kb deletion that is a beneficial modulating factor but not sufficient to explain this extremely mild phenotype. This unusual genotype/phenotype association is discussed in terms of the mechanisms underlying hemoglobin switching during development.
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