Ubiquitous dysregulation of the Wnt pathway in immune thrombocytopenia genetic susceptibility.

The pathogenesis of immune thrombocytopenia (ITP) is complex and incompletely understood. Multiple cell types have been implicated, and their respective contribution is unclear. A recent genome-wide association study identified single-nucleotide polymorphisms (SNPs) associated with pediatric ITP within or near 5 genes in the canonical Wnt signaling pathway. To investigate whether this pathway was dysregulated in ITP and identify which cell types were involved, we leveraged extensive functional genomics and single-cell RNA sequencing (scRNA-seq) data. By linking the identified SNPs to likely regulated genes, we showed an enrichment in the Wnt pathway and identified 2 additional genes in this pathway involved in ITP. The SNPs affected regulation of the Wnt pathway genes in multiple cell types. Indeed, scRNA-seq showed some of these genes were expressed in lymphocytes, whereas others were expressed in platelets or megakaryocytes. By comparing the cell-specific expression of these genes between individuals with ITP and healthy controls, we demonstrated that several genes in the Wnt pathway were differentially expressed between these 2 groups. Some genes were upregulated, whereas other were downregulated in ITP. In sum, the Wnt signaling pathway is broadly dysregulated in ITP, with a complex pattern that varies across genes and cell types.