Primary SS in adults can be diagnosed according to the Revised International Classification Criteria for SS from the American-European Consensus Group if four of the following six criteria are met: presence of ocular symptoms, presence of oral symptoms, evidence of keratoconjunctivitis sicca, focal sialadenitis upon minor salivary gland biopsy, instrumental evidence of salivary gland involvement, and the presence of SSA or SSB antibodies. This evidence concerns the gene SSB and Keratoconjunctivitis sicca.