Systematic autoantigen analysis identifies a distinct subtype of scleroderma with coincident cancer

Significance In this study, we created a barcoded whole-genome ORF mRNA display library and combined it with phage-immunoprecipitation sequencing to look for autoantibodies in sera from patients with scleroderma who also had coincident cancer without a known autoantibody biomarker. Using these two technologies, we found that 25% of these patients had autoantibodies to RNA Binding Region Containing 3 (RNPC3) and multiple other components of the minor spliceosome. There was evidence of intra- and intermolecular epitope spreading within RNPC3 and the complex. These combined technologies are highly effective for rapidly discovering autoantibodies in patient subgroups, which will be useful tools for patient stratification and discovery of pathogenic pathways.