Acetylator polymorphism in rheumatoid arthritis.

Acetylator phenotype has been determined with sulphamethazine (sulphadimidine) in 69 Spanish patients with rheumatoid arthritis (48 females), all of whom were on second line therapy, and in 96 age-matched normal controls (54 females). Thirty-two patients (46.4%) and 56 controls (58.3%) were classified as slow acetylators. On analysing separately the females in both groups, 37.5% of patients and 63% of controls were found to be slow acetylators. No difference was found in the males (patients 66.3% and controls 52.4% slow acetylators). Rapid acetylator phenotype may be a risk factor for the development of severe rheumatoid arthritis in women.