TNFSF13B and synovial sarcoma: After stratification of SS patients according to the presence or not of the A allele (A/G-A/A vs. GG), a significantly higher IGFIEa gene expression in MSG tissues (6.0 ± 2.5 vs. 3.0 ±3.3, p = 0.016) and B-cell activating factor (BAFF) serum protein levels (1774 ± 1529 vs. 868.5 ± 309.4 pg/mL, p = 0.03, measured in a previous study [36]) was found in A allele carriers compared to non-carriers (data not shown).