Characteristic hematological analyses of KLF1 heterozygotes in cohorts A and B. (A) MCV and MCH values in normal individuals (n = 1946 from cohort A), nonthalassemics (n = 41; 25 from cohort A and 16 from cohort D), and 7 KLF1–heterozygous mutations, β⁰-thalassemia heterozygotes (n = 217 from cohort B), and β⁰-thalassemia heterozygotes coinherited with KLF1 mutations (n = 14; 7 β⁰/β^N of 11 from cohort B and another 7 β⁰/β^N from 6 β-thalassemia families with KLF1 mutations; supplemental Figure 2). The α-thalassemia deletions or point mutations were excluded in all nonthalassemic and heterozygous β⁰-thalassemia individuals with and without KLF1 mutations. The data shown are expressed as mean ± SD. P value was determined using the Mann-Whitney U test. (B) HbA₂ and HbF levels in normal individuals (left) and β-thalassemia heterozygotes (right) with or without KLF1 mutations (all have normal α globin genotypes). (Left) Solid circles represent samples with KLF1 mutations, including 25 from cohort A (blue), 16 from cohort D (green), and 50 without KLF1 mutations (black; HbA₂, 2.81 ± 0.20%; range, 2.50% to 3.20%; HbF, 0.23 ± 0.22%, range, 0.00% to 0.80%). (Right) Solid circles represent 14 samples with KLF1 mutations (red) and 50 without KLF1 mutations (black; HbA₂, 4.96 ± 0.49%, range, 3.70% to 6.10%; HbF, 0.93 ± 0.70%, range, 0.20% to 4.10%). Genotype symbols of subjects are shown on the bottom right of the chart.