Moreover, there are also several lines of proofs undergirding the fact that dry mouth and dry eyes do not solely result from gland destruction, and that other mechanisms, including the presence of anti-muscarinic autoantibodies, altered mucin expression, nitric oxide-mediated salivary gland dysfunction, and modified aquaporin-5 (AQP5) distribution are also potential active players responsible for the sicca syndrome. This evidence concerns the gene AQP5 and dry eye syndrome.