As shown on Fig. 1, IEF (on polyacrylamide gel) revealed the presence of an abnormal component with an isoelectric point (pI) very slightly higher (ca. 0.02 pH unit) than that of Hb A (pH 6.95). This band migrated between the positions of Hb A and Hb Chicago [a136 (H19)Leu→Met] [5], another neutral variant. Isoelectric focusing on agarose gel as well as the electrophoresis done under various experimental conditions, failed to reveal any abnormal Hb. Cation exchange HPLC also showed a normal profile with Hb α2 amounting to 2.6% and Hb F to less than 1%. In contrast, reversed phase HPLC showed an abnormal a chain, more hydrophobic than the normal one, with a retention time (RT) of 23.5 on an arbitrary scale where the RTs of b- and a-globins are 10.0 and 20.0, respectively (Fig. 2) [4]. The abnormal a chain amounted  to 29% of the total a chains.

      The isopropanol instability test was positive after an incubation of 30 min. at 37°C, while the heat instability test was negative. DNA sequencing showed a mutation in codon 76 of the α2 gene (ATG→ATA) (Fig. 3), which leads to the replacement of a methionine residue by an isoleucine. This variant has not been previously described and was named Hb Hellux, an amalgamation of the carrier’s country of origin and the one where he now lives.

Figure 1. The IEF on polyacrylamide gel. Lane 1: hemo­lysate from a patient with Hb Chicago [α136 (H19)Leu→ Met (α2)]; lanes 2 and 4: hemolysate from the proband with Hb Hellux [α76 (EF5)Met→Ile (α2)]; lane 3: sample containing an increased amount of Hb F.

Figure 2. Reversed phase HPLC analysis of the globin from the proband with Hb Hellux [a76(EF5)Met®Ile (a2)].

Figure 3. DNA sequence analysis