Recently, Cook et al. (2020) used 5′ RACE PCR to amplify TCRβ chain and Sanger sequencing to analyze the TCR repertoire of the regulatory CD4+ T cell (Treg) population and found that the TCR repertoire of gluten-specific CD39+ Tregs in celiac disease patients was oligoclonal compared to healthy controls, suggesting that the repertoire of gluten-specific CD39+ Tregs may be driven by the specific antigen and the corresponding human leukocyte antigen (HLA) restriction. The gene discussed is ENTPD1; the disease is celiac disease.