Fetal hemoglobin in normal adults and ?-thalassemia heterozygotes

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 (HbF) in blood of normal adults and beta-thalassemia (beta-thal) heterozygotes with ten different types of mutations. Preparative PolyCAT-HPLC greatly facilitated the characterization of isolated HbF, i.e., the determination of the relative quantities of the G gamma and A gamma 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 (less than 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 -- G gamma -- G gamma -- arrangement and a C----T mutation at position -158 relative to the Cap site of both G gamma genes. The effect of the same mutation in the normal -- G gamma -- A gamma-arrangement was variable. Certain beta-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. G gamma values varied and often fell into two groups (high G gamma and low G gamma); high G gamma 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 beta-thal heterozygotes with any one of nine of the ten mutations were twice that of normals; the one exception was the beta-thal heterozygote with the IVS-I-6 (T----C) mutation with an average low Hb A2 value of 3.6%.