Fas and Fas ligand gene polymorphisms in primary Sjögren's syndrome. 
To screen for polymorphisms in the apoptosis regulating Fas and Fas ligand (FasL) genes in patients with primary Sjögren's syndrome (SS), and to explore associations with susceptibility to the disease.  Polymorphisms in Fas and FasL of 70 patients with primary SS and 72 controls were determined by polymerase chain reaction combined with the restriction enzyme fingerprinting single strand conformation polymorphism technique, verified by automatic sequencing and natural or amplification created restriction site tests.  Polymorphisms were found in both Fas and FasL, but only some of the Fas polymorphisms were found in statistically significant differences between patients and controls.  Patients displayed a higher frequency of the G/G genotype at position -671 than the controls, and the -671 G allele frequency for primary SS was increased compared to controls.  A higher frequency of the C allele at position IVS2nt176 and IVS5nt82 was also found.  Of note, the nucleotide variants in intron 2 and intron 5 were associated.  We describe the positions and frequencies of several polymorphisms in the genes encoding Fas and FasL in patients with primary SS.  None caused any amino acid change.  Three Fas alleles, of which one is located in the promoter area, showed significant although modest differences between patients and controls.