Several AD risk genes like IL1RL1, IL18R1, IL18RAP, ADAD1, KIAA1109, LRRC32, STAT3, RTEL1, ZGPAT, SLC9A4, IL13, C11orf30, TNFRSF6B, IL2/IL21 have also been linked with IBD suggesting a genetic relationship between the two [27]. The gene discussed is IL21; the disease is Alzheimer disease.