TNFRSF13C and Buschke-Ollendorff syndrome: We also observed that 12 and 13 transcripts related to immunoglobulins are downexpressed in BOS (PRED and DIAG, respectively) compared to STA, while gene expression of BAFF (B cell activating factor coded by TNFSF13B) and BAFF-R (BAFF receptor coded by TNFRSF13C), required for B cell survival and maturation, were not different between the three situations (data not shown).