SDC1 and monoclonal gammopathy: BM CD138+ plasma cells from 10 newly diagnosed or relapsed patients with POEMS syndrome, including a variant with undetectable monoclonal gammopathy (18); newly diagnosed patients with MM and MGUS (2 patients each); and 2 patients with early-stage lymphoma without BM invasion as controls were subjected to scRNA-Seq in this study (Supplemental Tables 1 and 2; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.151482DS1).