Figure 1From: Trait-stratified genome-wide association study identifies novel and diverse genetic associations with serologic and cytokine phenotypes in systemic lupus erythematosusSerum IFN-α levels in SLE patients stratified by SNP genotype at PTPRM (a) and LRRC20 (b). Y-axis shows the serum IFN-α activity score as outlined in the Methods section. Bars show the median, error bars show the interquartile range. Because IFN-α levels were far from normally distributed, we used a non-parametric version of the two sample t-test (non-parametric Mann-Whitney U) to test if IFN-α levels varied significantly between the two homozygous genotype groups.Back to article page