RESUMO
We report four unrelated families with a mild ß(+)-thalassemia (ß(+)-thal) allele consisting of two sequence variants at the 3' end of IVS-II: IVS-II-839 (T>C) (HBB: c.316-12T>C) and IVS-II-844 (C>A) (HBB: c.316-7C>A). These sequence variants alter the conserved polypyrimidine tract of the consensus splice acceptor sequence (Y11NYAG/G), which could reduce splicing efficiency. This may represent a common, yet under-diagnosed ß(+)-thal allele in African populations.
Assuntos
Mutação , Globinas beta/genética , Talassemia beta/genética , Adolescente , Adulto , Idoso , Alelos , Sequência de Bases , Criança , Pré-Escolar , Códon , Análise Mutacional de DNA , Feminino , Genótipo , Humanos , Lactente , Recém-Nascido , Íntrons , Masculino , Pessoa de Meia-Idade , Sítios de Splice de RNA , Adulto Jovem , Talassemia beta/sangue , Talassemia beta/diagnósticoRESUMO
We report the case of a father and daughter who are heterozygous for a duplication of 65 bp within exon 2 of the ß-globin gene, resulting in an altered and truncated ß-globin chain that is predicted to be non functional. The ß-globin gene mutation is in cis with the common Hb A2â' missense mutation of the δ-globin gene (HBD: c.49G>C), resulting in ß-thalassemia (ß-thal) trait with normal levels of Hb A2. This is the second report of this ß(0)-thal mutation, and both families were associated with the Hb A2â' variant and normal levels of Hb A2. Laboratories should be aware of the rare occurrence of ß-thal trait with normal levels of Hb A2.