Random forest analysis with expression levels of all 15 probe sets (panel A) shows the relative impact of individual genes on the accuracy when differentiating biliary atresia from diseased controls. In panel B, the accuracy improves for IL8 and LAMC2 as a subgroup. In panel C, subjecting IL8 and LAMC2 as individual values or combined as a first principal component (FPC) to ROC curves identifies livers of subjects with biliary atresia at the specified values. Considering IL8 and LAMC2 combined as FPC (green line in [C]), the area under curve is 0.934, sensitivity is 96.9%, and specificity is 85.7%. In panel D, scatter plots show the serum concentration of IL8 for infants at the time of diagnosis of biliary atresia (BA; N=81) compared to non-biliary atresia (non-BA; N=66) and normal control (NC; N=5). The average concentrations for BA and non-BA are not different. Values are expressed as mean ± SEM; *P<0.05, **P<0.01. In panel E, ROC curves of serum IL8 to differentiate samples from biliary atresia and diseased controls has sensitivity of 63.0% and specificity of 53.0%, with the ideal cutoff value as 117.8 pg/mL.