CD4 and inflammatory bowel disease: To better understand if and how the RORC rs4845604 variant affects CD4+ T cell differentiation events, we compared both the cellular differentiation and transcriptional response of purified naïve CD4+ T cells ex vivo from nine subjects homozygous for the rs4845604 A allele (a protective IBD association), with nine subjects homozygous for the G allele (a risk allele for IBD).