A Fas promoter polymorphism at position-670 in the enhancer region does not confer susceptibility to Felty's and large granular lymphocyte syndromes

Objective. We examined whether there are associations between a polymorphism in the Pas promoter, recently found to be associated with rheumatoid arthritis (RA), and Felty's syndrome or large granular lymphocyte (LGL) leukaemia. Methods. Thirty-five patients with Felly's were studied, along with 18 patients with LGL syndrome and arthritis, 17 patients with LGL syndrome but no arthritis, and 128 controls. The polymorphism was typed by polymerase chain reaction followed by digestion with the restriction enzyme MvaI. Results. No significant difference was found in genotype or allele frequencies between the groups. Conclusion. This promoter polymorphism is not a significant risk factor responsible for the LGL expansions seen in Felty's and LGL syndromes. Abnormal, constitutive expression of Fas ligand may be more relevant to the aetiology of these diseases.