Clinical data showing CYB5R3 T117S lessens the HbF, Hct, and total Hb responses to HU treatment in Walk-PHaSST patients. (A) Experimental design for clinical data analysis. (B) HbF (%) in patient samples by different CYB5R3 genotypes and HU treatment status, analyzed using a 2-way analysis of variance (ANOVA). (C-E) Hct (%) vs HbF (%) for the different CYB5R3 genotypes (x-axis truncated at 20% HbF; full-scale x-axis data available in supplemental Figure 1C-E), analyzed by simple linear regression. (F-H) Hb (g/L) vs HbF (%) for the different CYB5R3 genotypes (x-axis truncated at 20% HbF; full-scale x-axis data available in supplemental Figure 1F-H), analyzed by simple linear regression. The dotted lines in these figures show where the 2 lines meet, and the point of intersection is mentioned adjacent to the line. (I) Percentage of HbF in HU^pos patient samples vs age for the different CYB5R3 genotypes analyzed by simple linear regression. Data are expressed as mean ± standard error of the mean unless otherwise specified. A comparison of the linear regression lines for the differences between slopes used a method equivalent to analysis of covariance (ANCOVA). A value of P < .05 was considered significant. In all correlation graphs, the P value is for the difference between the slopes in each graph. db SNP, single nucleotide polymorphism database; HU^neg, HU untreated; HU^pos, HU treated; MCV, mean corpuscular volume.