Asymptomatic homozygous deletional β0‐thalassemia in an African individual

• Published in: American journal of hematology 2002-07, Vol.70 (3), p.232-236
• Main Authors: Faustino, Paula, Reis, Ana Batalha, Feliciano, Helena, Ferrão, Lénia, Pereira, Patrícia, Picanço, Isabel, Miranda, Armandina, Seixas, Teresa, Romão, Luísa, Júnior, Esmeraldina Correia, Lavinha, João
• Format: Article
• Language: English
• Subjects: Anemias. Hemoglobinopathies; Biological and medical sciences; deletion; Diseases of red blood cells; Hb F; Hb switching; Hematologic and hematopoietic diseases; Medical sciences; thalassemia; β‐globin gene
• ISSN: 0361-8609; 1096-8652
• DOI: 10.1002/ajh.10118

Homozygosity or compound heterozygosity for β0‐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 β0‐thalassemia. At the molecular level, this is the first description of homozygosity for the β0‐Black 1,393‐bp deletion. In this case, the complete absence of β‐globin gene expression seems to be compensated by an unusually high fetal globin gene expression (Hb F 96%). β‐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 Gγ‐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 α‐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. Am. J. Hematol. 70:232–236, 2002. © 2002 Wiley‐Liss, Inc.