TRIM21 and synovial sarcoma: It is noticeable that in contrast to what was observed with the sera from lupus mothers, the sera from mothers with SS reacted with fewer Ro peptides; namely, four Ro52 peptides (sequences 1–13, 107–122, 277–292 and 365–382) and two Ro60 peptides (sequences 21–41 and 304–324), which were recognized by at least 25% of sera.