Regarding cytokines, plasma concentrations of IFNg (p = 0.7881), IL1a (p = 0.9374), IL1b (p = 0.9484), IL2 (p = 0.6985), IL6 (p = 07950), TNFα (p = 0.6791) were not statistically different between PKU patients and healthy controls (Figure 2). Here, IL2 is linked to phenylketonuria.