Nonetheless, examination of intestinal biopsy samples from people with and without Crohn’s disease and quantification of CYP3A4 expression by Western blotting indicate a significant decrease in protein expression of CYP3A4 in the ileum (by 45%) and colon (by 78%) in subjects with Crohn’s disease relative to subjects without it [421]. The gene discussed is CYP3A4; the disease is Crohn disease.