Surprisingly, when KRN mice were crossed with NOD mice, the progeny, i.e., the KRN Tg TCR in {B6xNOD}F1 mice, developed arthritis with severe joint inflammation, which depended on the presence of Tg TCR and Ab with specificity to glucose-6-phosphate isomerase (GPI) [24]. The gene discussed is GPI; the disease is arthritic joint disease.