Using a large cohort of patients with well-defined PTLD, this study found that RF and ACPA testing were frequently utilized clinically, though these autoantibodies were found infrequently in this population. Most of those with positive serologies had low-titer RF or ACPA, and only a small portion were later diagnosed with RA. The gene discussed is PRTN3; the disease is post-transplant lymphoproliferative disease.