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 polymorphis m in the Pas promoter, recently found to be associated with rheumatoid arth ritis (RA), and Felty's syndrome or large granular lymphocyte (LGL) leukaem ia. Methods. Thirty-five patients with Felly's were studied, along with 18 pati ents 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 frequenc ies between the groups. Conclusion. This promoter polymorphism is not a significant risk factor res ponsible for the LGL expansions seen in Felty's and LGL syndromes. Abnormal , constitutive expression of Fas ligand may be more relevant to the aetiolo gy of these diseases.