A polymorphism affecting the CD4 gene (CD4) enhancer is associated with susceptibility to both rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), a study of Taiwanese patients suggests.
Sui-Foon Lo and colleagues at China Medical University Hospital in Taichung, Taiwan, prospectively enrolled 192 patients with RA, 141 with SLE, and 96 healthy controls.
All were genotyped for the –11743A/C and –10845A/G polymorphisms in the CD4 enhancer region, which plays a major role in regulating CD4 transcription in T cells.
Reporting their findings in the Journal of Rheumatology, the authors state that, for the –11743A/C polymorphism, RA patients had a higher frequency of the C allele versus controls, whereas SLE patients had a higher frequency of the CC genotype and a lower frequency of the AC genotype versus controls.
For the CD4 –10845A/G polymorphism, RA and SLE patients had significantly higher frequencies of the A allele and AA genotype versus controls while SLE patients also had a lower frequency of the GG genotype than controls. All reported associations were statistically significant.
The CD4 polymorphisms were also associated with mucosal ulcer lesions in patients with SLE.
Lo et al say that the polymorphisms “may have affected CD4 gene expression and conferred risk for developing RA and SLE,” possibly by a mechanism leading to tolerance or susceptibility to autoimmunity.
“Our study suggests that the genetic polymorphism at the CD4 enhancer can serve as a genetic marker for the risk of development of RA and SLE,” they conclude.
“However, the exact mechanism of such association needs to be further investigated.”