CD4 and cranioectodermal dysplasia: In celiac disease (CeD), cereal-derived gluten peptides penetrate the small intestinal barrier, are subsequently modified by tissue trans-glutaminase 2 (TG2), then presented by HLA-DQ2- or HLA-DQ8-positive antigen-presenting cells (APCs) to gluten-specific CD4+ T-helper cells (gsTcells)1.