| Autor: |
Baklouti, F, Ouazana, R, Gonnet, C, Lapillonne, A, Delaunay, J, Godet, J |
| Zdroj: |
Blood; October 1989, Vol. 74 Issue: 5 p1817-1822, 6p |
| Abstrakt: |
An atypical sickle cell trait with a very low level of hemoglobin S and features of heterozygous beta-thalassemia was recently described. In vitro globin chain synthesis strongly suggested the presence of the two abnormalities on the same chromosome. We report the corresponding beta S-thal gene. DNA sequence revealed a C----T base substitution in the distal promoter element CACCC, at position-88 from the cap site, in addition to the expected GAG----GTG mutation responsible for the structural variant (beta 6 Glu----Val). Reticulocyte mRNA titration and transient assay of the mutant gene in COS cells showed a defect in beta- mRNA production. Restriction haplotype and DNA sequence analyses revealed that the doubly mutated gene is associated with haplotype 19 (or Benin/Algeria haplotype). In particular, we found the (AT)9(T)4 repeated sequences specifically encountered 5' to the beta S gene of Benin Algeria type. These results support the view that the beta S-thal gene resulted from an independent thalassemic mutation having occurred on a beta S chromosome rather than (a) from a beta S mutation having altered a beta-thalassemic gene or (b) from a recombination event between two chromosomes, each carrying one of the mutations. |
| Databáze: |
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