Sjögren's syndrome

Sjögren's syndrome (SS) is a progressive autoimmune rheumatic disorder.^1-6 Its precise etiology is unknown, although several contributing factors have been identified. One theory is that the condition results from complications related to infection with the Epstein-Barr virus.⁴ Primary exposure to or reactivation of Epstein-Barr virus elicits expression of the human leukocyte antigen complex. This is recognized by T lymphocytes (CD 4⁺) resulting in the release of cytokines (tumor necrosis factor, interleukin-2, interferon-gamma, and others). A genetic marker specific for Sjögren's syndrome, HLA-DR4, has been identified.^1,2 According to the World Health Organization, the prevalence of Sjögren 's syndrome is unknown.⁷ A recent epidemiologic study in Sweden estimated the prevalence in the adult population to be 2.7%.⁸ In the United States, 10 years ago, the number of patients with Sjögren's syndrome was thought to be fewer than 100,000.⁹ This number today is estimated to be more than 1 million.¹⁰ Sjögren's syndrome has been reported in nearly every major country of the world, and the geographic distribution of cases appears to be relatively uniform.¹¹ Sjögren's syndrome typically affects women (90%) during the fourth or fifth decade of life.¹² Isolated cases of Sjögren's syndrome in children have been reported.¹³.