Footnotes

• Handling editor Josef S Smolen

• Twitter @JBVulsteke

• EDL and XB contributed equally.

• Contributors J-BV, EDL and XB designed the study, analysed the data and drafted the manuscript. J-BV performed the immunoprecipitation-western blot experiments. YP, CB, PV, DB, SV, KC, PDH, JLL, WAW, VS and EDL collected patient data and revised the draft manuscript. TM provided reference material and revised the draft manuscript.

• Funding JB Vulsteke holds a Research Foundation—Flanders (FWO) SB Fellowship (1S62419N).

• Competing interests WAW has received research grants from Roche, Boehringer-Ingelheim and Galapagos. VS has received research grants and support from Boehringer-Ingelheim and Janssen-Cilag, and research support from Accord Healthcare, UCB, and Celgene. XB was part of a scientific advisory committee for Inova Diagnostics and Thermo Fisher (outside the scope from the submitted work).

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

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