We demonstrate that dominant IgG4+ B‐cell receptor (BCR) clones determined by next‐generation sequencing accurately distinguish patients with IgG4‐associated cholangitis/autoimmune pancreatitis (n = 34) from those with primary sclerosing cholangitis (n = 17) and CA (n = 17). The gene discussed is BCR; the disease is sclerosing cholangitis.