title: Molecular and cellular characterization of a new α-thalassemia mutation (HBA2:c.94A>C) generating an alternative splice site and a premature stop codon.
abstract: The identification of α-thalassemia (α-thal) due to point mutations has been increasing significantly with the advancement of molecular diagnostic tools. We describe here the molecular and cellular characteristics of the thalassemia mutation HBA2:c.94A>C, a novel point mutation affecting the α2-globin gene, causing a mild α-thal phenotype in a male patient of undisclosed ethnicity, investigated for unexplained microcytosis. The detected mutation is located at the penultimate nucleotide (nt) of the first exon which we postulated might affect pre mRNA splicing. While an in silico analysis did not predict any aberrant splice variants, experimental analysis using our in vitro model for gene expression studies showed utilization of a cryptic splice site at codon 15 that resulted in an aberrant splice variant. As a result, a frameshift in the reading frame of the mature mRNA was produced, leading to the formation of a premature termination codon (PTC) between codons 48 and 49 in exon 2. This in turn leads to nonsense mediated mRNA decay (NMD) and the phenotype of α-thal.
authors.affiliation: Department of Haematology, PathWest Laboratory Medicine, Queen Elizabeth II Medical Centre, Nedlands, WA 6009, Australia.
authors.forename: Talal
authors.initials: T
authors.lastname: Qadah
authors.forename: Jill
authors.initials: J
authors.lastname: Finlayson
authors.forename: Christopher
authors.initials: C
authors.lastname: Newbound
authors.forename: Nicole
authors.initials: N
authors.lastname: Pell
authors.forename: Michelle
authors.initials: M
authors.lastname: Pascoe
authors.forename: Laura
authors.initials: L
authors.lastname: Greenwood
authors.forename: Paula
authors.initials: P
authors.lastname: Holmes
authors.forename: Dianne
authors.initials: D
authors.lastname: Grey
authors.forename: John
authors.initials: J
authors.lastname: Beilby
authors.forename: Reza
authors.initials: R
authors.lastname: Ghassemifar
mesh_terms: D000328:Adult; D001483:Base Sequence; D018389:Codon, Nonsense / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D006443:Hemoglobin A2 / Q000235:genetics*; D006455:Hemoglobins, Abnormal / Q000235:genetics; D006801:Humans; D008297:Male; D017354:Point Mutation; D022821:RNA Splice Sites / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D055542:alpha-Globins / Q000235:genetics; D017085:alpha-Thalassemia / Q000175:diagnosis / Q000235:genetics*
chemical_list: D018389:Codon, Nonsense; D006455:Hemoglobins, Abnormal; D022821:RNA Splice Sites; D055542:alpha-Globins; D006443:Hemoglobin A2