Hb Etobicoke, α85(F5) Ser → Arg Found in a Newborn of French-Indian-English Descent

Abstract

During a recent testing program for hemoglobin (Hb) abnormalities in cord bloods of newborns in the State of Georgian an α-chain variant was discovered in a male Caucasian infant of French-Cherokee Indian-English descent. The hematological values of the infant at five weeks were: Hb 8.9 g/dl, RBC 2.99 × 10¹²/1; PCV 0.28 1/1, MCV 93 fl, MCH 30.4 pg, and MCHC 31.2%. Corresponding results on both parents were normal. Although the abnormal Hb was not found in either parent, paternity studies were not done. The variant had a mobility of Hb G on cellulose acetate electrophoresis at PH 8.6 and could not be detected by citrate agar electrophoresis at pH 6.1 (1). DEAE-cellulose chromatography with glycine-KCN-NaCl developers (2) redily separated the abnormal Hbs from Hb A, Hb F, and Hb F₁ partially separated Hb F_x from Hb X. The combined concentration of the Hb F_x was 16% in the cord blood red cell lysate. A repeat chromatogram at five weeks of age showed improved separation and gave the concentration of Hb F_x as 13.4% and Hb X as 3.7%. The abnormal Hb was completely separated from the other Hbs by high performance liquid chromatography (HPLC), (3) as illustrated in Figure 1. Hb F_x showed a concentration of 17.8% (corresponding to 20.8% of the total Hb F) and Hb X of 3.2% (Corresponding to 22.9 of the total Hb A). The Hb chains were separated by chromatography on CM-cellulose according to the method of Clegg et al (4). The abnormal α-chain was digested with TCPK-trypsin and the resulting peptides separated by HPLC (5). All soluble peptides had the expected mobility except for an extra peptide which appeared after αT-14 in the beginning of the chromatogram. Amino acid analysis of this zone (αT-9b) gave the same composition [Asp 1.03 (1), Ala 1.14 (1), Leu 0.92(1), His 1.93(2), Lys 0.99 (1)] as the last part of the αT-9 peptide (residues 85–90, inclusive). Amino acid analysis of the normally appearing αT-9 gave the following composition: Asp 5.28(5), Thr 1.02(1), Ser 1.08(2), Pro 1.00(1), Ala 5.70(6), Val 3.20(3), Met 0.83(1), Leu 3.06 (3), His 0.97(1), Arg 0.85(0), which suggested that this αT-9a peptide was the first part of the αT-9 peptide except for the replacement of a sery1 residue at position α84 by an arginyl residue. An αT-8, 9a peptide eluted behind the abnormal αT-9a fragment.