CD2 and celiac disease: Based on cluster analysis performed with the k-means method, three groups (clusters) of children with varying TOC and TAC levels including two groups of children with celiac disease were identified: CD1 (n = 17/56) with mean TAC levels of 1.80 mmol/L and mean TOC levels of 0.167 mmol/L; CD2 (n = 15/56) with TAC/TOC levels of 0.89 mmol/L and 0.41 mmol/L, respectively; and the third group consists of healthy children (n = 24/56) with mean TAC levels of 1.34 mmol/L and mean TOC levels of 0.29 mmol/L (Figure 1).