RESUMO
We report the case of a woman with ß(+)-thalassemia (ß(+)-thal) trait, in which there were two sequence variants within the ß-globin gene promoter: -54 (G>A) [HBB c.-104G>A] and -26 (A>C) [HBB c.-76A>C]. Data from other patients indicate that the -54 substitution is a non pathogenic sequence variant. Therefore, the ß-thal phenotype is most likely due to the -26 mutation that is adjacent to the conserved ATAA box.
Assuntos
Regiões Promotoras Genéticas , Globinas beta/genética , Talassemia beta/genética , Região 5'-Flanqueadora , Adulto , Sequência de Bases , Feminino , Heterozigoto , Humanos , Masculino , Dados de Sequência Molecular , Mutação , Fenótipo , Polimorfismo de Nucleotídeo Único , Globinas beta/biossínteseRESUMO
We report the identification of three, new beta-thalassemia (beta-thal) mutations with varying degrees of severity. The most severe mutation, a frameshift mutation in exon 3 of the beta-globin gene [codon 120 (-A)], was associated with a dominant beta-thal phenotype. A second frameshift mutation, codon 50 (-T), resulted in a phenotype of typical high Hb A(2) beta-thal trait. The mildest mutation was IVS-II-2 (T > C), which changes the splice donor sequence of IVS-II from GT to GC. This transition mutation resulted in a slight reduction in beta-globin gene expression and could be considered a mild beta(+)-thal allele.
