Genetic markers in Sjögren's syndrome: the question of its genetic heterogeneity.

Genetic factors may be implicated in the causation of Sjögren's syndrome (SS) as shown by familial clustering of the disease and certain HLA associations. Non-HLA genetic markers in SS have not previously been studied in detail. In this study of 122 unrelated patients with various categories of SS and 104 control subjects, 29 genetic markers were studied (11 blood groups, 5 serum proteins and 13 red-cell enzymes). Almost all systems showed a considerable range of gene frequency among the various subgroups of patients with SS but only a few attained statistical significance (C3 and GPT). Multivariate (kinship) analysis, however, showed clear distinction between the subgroups of SS, suggesting that they are genetically distinct entities.