PSMG1 and inflammatory bowel disease: Finally, a GWA study carried out in pediatric-onset IBD patients identified two novel IBD loci located on chromosome 20q13 and 21q22, close to the tumor necrosis factor receptor superfamily member 6B (TNFRSF6B) and proteasome-assembling chaperone 1 (PSMG1) genes [10].