Abstract
Globin synthesis in β-thalassemia major without anemia. A 2½ year old girl (N.B.) with homozygous β-thalassemia (thal.) with only mild anemia (Hb 10.6-12.8 g/dl) and with complete absence of HbA, which is replaced by 1.3 % HbA2 and the rest being HbF, is presented. Her parents show both heterozygous β-thal. with increased HbA2 (5.5-5.9%) and HbF (6.0-6.9%). The disease of N.B. differs from homozygous forms of β° -thal. by the absence of severe anemia, of β+-thal. by the lack of HbA and from βδ-thal. or hereditary persistence of HbF (HPFH) by the presence of HbA2. Her β-thal. is similar to the one reported in two homozygous individuals of a dutch sib by Schokker et al (Nature 209:44,1966). Incorporation of 3H-leucine in reticulocytes and separation of the globin-chains confirms the absence of β-chain-synthesis in N.B. and the non α : α -chain synthetic ratios are unbalanced for N.B. (0.47) which is distinctly above the ratios reported for homozygous β°-thal. (0-0.2). Absence of severe anemia in homozygous βδ-thal. and HPFH was recently shown to be related to the absence of the δ-gene and its flanking DNA-sequences. Homozygous β° - thal. and β+-thal. was thus proposed to lead to severe anemia by the presence of a regulatory DNA-sequence near the δ-chain locus suppressing γ-chain-synthesis, which in βδ-thal. and HPFH replaces the lacking β-chains (A. Banks, Science 207:486, 1980). In N.B. the γ-chain-suppressor seems to be inactive as in βδ-thal. but the δ-gene is present, thus indicating the separation of the γ-regulatory gene from the δ-structural gene.
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Tuchschmid, P., Boller, E. & Duc, G. Globin synthesis in β-thalassemia major without anemia. Pediatr Res 14, 1422 (1980). https://doi.org/10.1203/00006450-198012000-00085
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DOI: https://doi.org/10.1203/00006450-198012000-00085