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ABSTRACT: This paper describes the phenotypic manifestations of a very mild β-thalassaemia mutation detected in several members of two families of Italian descent. The molecular defect, defined by denaturing gradient gel electrophoresis analysis and direct sequencing. consists of a C G substitution at position 844 of IVSII of the β-globin gene within the consensus sequence of IVSII acceptor splice site. Heterozygotes for this mutation show a haematological phenotype ranging in severity from silent β-thalassaemia to that of a mild β-thalassaemia carrier silent β-thalassaemia to that of a mild β-thalassaemia carrier state, whereas homozygotes have the typical manifestations commonly resulting from heterozygosity for a β-thalassaemia mutation. Compound heterozygotes for the IVSII nt844 (C G) mutation and a severe β-thalassaemia mutation have the phenotype of thalassaemia intermedia.
This paper indicates that the presence of borderline red blood cell indices or HbA2 values should make one suspect the presence of a very mild or silent β-thalassaemia.
British Journal of Haematology 11/1994; 88(3):562-565. DOI:10.1111/j.1365-2141.1994.tb05074.x · 4.96 Impact Factor