Footnotes

• ALM and AR contributed equally.

• Handling editor Josef S Smolen

• Contributors ALM, AR, RND and JLG designed the study, collected the data, analysed the results and wrote significant portions of the manuscript. TL, AZ, SJP, JS and JLG designed aspects of the study, collected the data and analysed the results. KP, LC-R and LML contributed to clinical data and analysed the results. All authors revised the manuscript critically for important intellectual content and approved the final version.

• Funding This work was financially supported by the Intramural Research Program of the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Cancer Institute of the National Institutes of Health. LC-R is funded in part by the Donald B and Dorothy L Stabler Foundation.

• Competing interests None declared.

• Patient consent Not required.

• Ethics approval NIH IRB.

• Provenance and peer review Not commissioned; externally peer reviewed.