Genetic contribution of the tumour necrosis factor (TNF) B + 2522/2 genotype, but not the TNFa,b microsatellite alleles, to systemic lupus erythematosus in Japanese patients

Summary The contribution of the tumour necrosis factor (TNF) B + 252 (TNFB) dimorphism and microsatellite polymorphisms of TNFa and TNFb to the pathogenesis of systemic lupus erythematosus (SLE) was studied in Japanese patients. The TNFB dimorphism was determined using the restriction fragment length polymorphism (RFLP) method with NcoI digestion followed by specific polymerase chain reaction (PCR) amplification. TNFa and TNFb microsatellite polymorphisms were determined using the DNA sequencer and GeneScan program (Applera Corporation, Foster City, CA) followed by specific PCR amplification. HLA‐DRB1*15 typing was carried out by the PCR‐sequence specific conformational polymorphism (SSCP) method. In SLE, the allele frequency of TNFB*2 significantly increased (68.9%, P