In controls, BAFF-R expression was closely associated with the proportions of circulating naive B cells and MBCs; however, in CIS/MS patients, this association was absent suggesting that the effects of BAFF/BAFF-R in maintaining homeostatic B cell differentiation may be impaired; whether this promotes survival of autoreactive MBC remains to be explored. This evidence concerns the gene TNFSF13B and in situ carcinoma.