Abstract
The abnormal Hb F‐Porto Torres [Aγ75(E19)Ile→Thr, 136(H14)Ala→Ser] was observed during a cord blood survey for hemoglobinopathies in North Sardinia. This silent variant showed the same mobility as Hb F‐Sardinia in isoelectric focusing (IEF) of the tetramers, whereas the abnormal globin chain was clearly separated by acid‐urea‐Triton polyacrylamide gel electrophoresis (AUT‐PAGE) from the normal Gγ‐ and Aγ‐globin chains. Separation of the globin chains by reversed phase high performance liquid chromatography (HPLC) indicated the following percentages: Gγ 68.4, Aγ 14.0, Xγ 17.6, that strongly suggested the abnormal chain as being a variant of the Aγ‐globin. Sequencing of the γ‐globin genes indicated that the mutated gene was in fact an Aγ with two nucleotide replacements, one being the ATA→ACA (Ile→Thr) at codon 75 (the so‐called AγT of the rather common Hb F‐Sardinia) and the second the GCA→TCA (Ala→Ser) at codon 136. This new variant is the seventh having the sequence of the AγT chain with an additional mutation so far described and the third characterized by gene sequencing.