PRTN3 and rheumatoid arthritis: The profile and complex interplay of various RA-associated auto-antibodies and their different isotypes is influenced by the ethnic, genetic and environmental factors, with RF isotypes having been shown to be associated with a poor prognosis in Chinese and Indian, but not in Malay RF patients6, while in Caucasians, ACPA-IgA have been shown to be associated with severe disease and radiographic progression11,12.