Interestingly, donor-derived MZB cells in B6 recipients had more differentially expressed genes compared with both B6 MZB cells and donor-derived MZB cells in Rag2–/– recipients, suggesting that lymphopenia enhanced the acquisition of the MZB cell transcriptional program in B cells (Figure 5B and Supplemental Figure 2B). The gene discussed is RAG2; the disease is lymphopenia.