Discrepancies are also found about the association with primary Sjögren's syndrome: studies based on patients with Sjögren's syndrome find a strong association with Ro52 Ab (26, 27), whereas studies based on Ro52 Ab positive sera are more heterogeneous, some showing an association with this disease (3, 12, 16, 18) and some showing a less frequent association than with Ro60 Ab (15). This evidence concerns the gene TRIM21 and Sjogren syndrome.