To analyse associations of two oestrogen receptor alpha (ORalpha) gene polymorphisms in 260 patients with SLE from northern Sweden. The two polymorphisms, PvuII T/C and the XbaI A/G, are located in the first intron of the ORalpha gene.
All patients fulfilling at least four of the ACR criteria for SLE were consecutively recruited during one year. The SLEDAI score and SLICC damage index were recorded. 670 individuals from the same geographical area served as controls. DNA from the patients and controls was extracted and genotyped using the 5' nuclease assay with an ABI PRISM 7900HT instrument. The genotype/phenotype relationships were calculated using SPSS.
The unusual PvuII C allele was associated with malar rash and the unusual XbaI G allele with photosensitivity (p = 0.001, OR = 2.53, 95% CI = 1.43 to 4.47 and p = 0.007, OR = 2.12, 95% CI = 1.22 to 3.66, respectively). The common XbaI AA genotype was associated with serositis (p = 0.013, OR = 1.92, 95% CI = 1.15 to 3.22). Based on the SLICC damage index associations of the common TT genotype and AA genotype with cognitive impairment were identified (p = 0.018, OR = 2.47, 95% CI = 1.17 to 5.25 and p = 0.018, OR = 2.75, 95% CI = 1.19 to 6.38 respectively). There was also an association of the XbaI AA genotype with the angina/coronary artery bypass variable (p = 0.042, OR = 2.58, 95% CI = 1.03 to 6.43). Of the variables describing disease severity and duration it was found that carriers of the unusual PvuII C allele showed a later onset of SLE (p = 0.02) and carriers of the unusual XbaI G allele a lower SLICC damage index.
The unusual PvuII C and XbaI G alleles were associated with a milder form of SLE characterised by skin manifestations, later onset, and less organ damage.