Fig. 1: Characteristics of DPD activity.

a Correlation between [UH2]:[U] and patient age. b Correlation between [U] and [UH2]:[U]. Horizontal lines represent the threshold [U] level for partial deficiency (blue) and complete deficiency (red), and vertical dashed lines represent the threshold [UH2]:[U] for partial deficiency (blue) and complete deficiency (red).