We analyzed four enzymes involved in the degradation of immunogenic gluten peptides that could be involved in reducing CeD symptoms (general N-type aminopeptidase (PepN), X-prolyl dipeptidyl aminopeptidase (PepX), endopeptidase (PepO), and endoprolyl peptidase (PREP). The gene discussed is PREP; the disease is cranioectodermal dysplasia.