A polymorphism in FAS gene promoter correlated with circulating soluble FAS levels.

The -670FAS (A/G) polymorphism and elevated concentrations of the soluble form of FAS (sFAS) have been associated with neoplasic and autoimmune diseases. This polymorphism in the Fas promoter gene could modulate the transcription of Fas expression and therefore, contribute to these pathologies. The in vivo functional significance of the FAS polymorphism was investigated by assessing the correlation between FAS genotypes and the serum-circulating FAS (sFAS) levels. We determined the FAS polymorphism distributions by restriction fragment-length polymorphism-polymerase chain reaction in 170 normal subjects. We used enzyme-linked immunosorbent assay to evaluate the sFAS levels in 44 of these individuals. Assessment of the concentration of sFAS indicated that the level of sFAS in subjects carrying the FAS-A/A genotype was significantly higher than that of those carrying the G/G genotype (3.90 ng mL(-1) vs. 3.12 ng mL(-1), P = 0.035). Our results demonstrated that FAS promoter polymorphism was significantly associated with the level of soluble FAS production in normal subjects.