Smokers who have certain variations of the estrogen-related ESR1 gene are at higher risk of developing lupus, a study suggests.
The research, “Estrogen receptor alpha gene (ESR1) polymorphism and its interaction with smoking and drinking contribute to susceptibility of systemic lupus erythematosus,” was published in the journal Immunology Research.
Estrogens are the most important female hormones and are produced mostly during the reproductive years. They bind to two estrogen receptors, ESR1 and ESR2.
Scientists have linked changes in the sequence of genes encoding the receptors to the development of some diseases. One such change is the replacement of one DNA base pair with another. The replacements are known as single-nucleotide polymorphisms, or SNPs.
Researchers didn’t know whether the DNA changes could influence the risk of someone developing lupus.
In addition to genetics, scientists have linked environmental factors such as smoking and drinking to the risk of lupus.
Chinese researchers decided to study how particular genetic and environmental factors might work together to influence lupus risk.
No study had covered whether the interaction between the ESR1 gene and smoking or drinking might play a role in the risk of a person developing lupus, the team noted. “So, the aim of this study was to investigate the impact of several SNPs within the ESR1 gene, and their interaction with smoking and alcohol drinking on SLE [lupus] susceptibility” among Chinese, the researchers said.
Using blood samples from 230 lupus patients and 462 healthy subjects, the team looked for SNPs in the ESR1 gene. They discovered that certain variations in the gene, such as the rs2234693 C allele and rs9340799 G allele, were significantly more common in lupus patients than in the control group.
The team combined these findings with other information on the patients, particularly whether they smoked and drank, to produce an analysis.
It showed that smokers with the rs2234693 genetic variation were at a much higher risk of developing lupus than non-smokers with a normal gene. This was true regardless of study participants’ gender, age, drinking, and body weight.
“In conclusion, we found that C allele of rs2234693 and G allele of rs9340799 within the ESR1 gene, [and the] interaction between rs2234693 and current smoking were all associated with increased SLE risk,” the researchers concluded.
One of the limitations of the study was the relatively small patient sample, the team said. Another was that the analysis covered a limited number of ESR1 gene SNPs.
And a third was lack of information about the menopausal status of the women in the study. The team did not look at the interaction between women’s hormone levels and whether they had lupus.