Individuals with a high PRS in TwinsUK did not show rheumatoid arthritis seropositivity: only nine (2%) of 500 individuals in the TwinsUK sample who had serum available were positive for ACPA, defined as more than 5 U/mL (table), and were distributed similarly across genetic risk groups, by PRS quartile (high 2:93; low 7:398). The gene discussed is PRTN3; the disease is rheumatoid arthritis.