Fetal hemoglobin in normal adults and ?-thalassemia heterozygotes

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Abstract
A recently developed high performance liquid chromatographic (HPLC) procedure using a weak cation exchanger (PolyCAT) in columns of different sizes was used to quantify fetal hemoglobin (Hb F) in blood of normal adults and β-thalassemia (β-thal) heterozygotes with ten different types of mutations. Preparative PolyCATHPLC greatly facilitated the characterization of isolated Hb F, i.e., the determination of the relative quantities of the Gγ and Aγ chains. The method is accurate and allows quantitation of Hb F at the 0.5% level; preparative PolyCAT-HPLC allows isolation of (nearly) pure Hb F from blood samples with low (< 1%) Hb F. Adult Hb F levels were determined in 69 normal adults (including 24 diabetics); Hb F levels fell below 1% except for subjects with abnormal -Gγ-Gγ arrangement and a C→T mutation at position -158 relative to the Cap site of both Gγ genes. The effect of the same mutation in the normal-Gγ-Aγ-arrangement was variable. Certain β-thal mutations (namely, those at positions -29;-88; IVS-I-1; IVS-II-1) were associated with high Hb F levels in heterozygotes, while those at nucleotide (nt) positions IVS-I-6; IVS-I-110; codon 24; codon 39; codons 41/42; IVS-II-745 were not. Gγ values varied and often fell into two groups (high Gγ and low Gγ); high Gγ values were not associated with high Hb F values. The chromatographic procedure is ideally suited for Hb A2 quantitation. Average values of Hb A2 in β-thal heterozygotes with any one of nine of the ten mutations were twice that of normals; the one exception was the β-thal heterozygote with the IVS-I-6 (T→C) mutation with an average low Hb A2 value of 3.6%.