= 9.67×10−5). The MAF of the ‘A’ allele increased from 8% in controls to 11% in all SLE cases, 15% in cases positive for aCL IgG, and 20% in cases with aCL IgG>40. Additional analyses suggest a positive correlation between risk allele ‘A’ and higher aCL IgG titer in 1251 available European samples (cases or controls) when aCL IgG titer used as a phenotype in quantitative analyses tests (qtl) (P = 0.009). Moreover, 42% of these aCL positive lupus patients are also diagnosed with anti-phospholipid syndrome (APS) with sufficient evidence of thrombosis (peripheral, cerebral, cardiac or pulmonary). We observed similar results in our EA population; 50 lupus patients with aCL-positive APS compared to healthy control (P = 0.003, OR = 2.17, 95%CI = 1.26–3.74; FDR = 0.03). A similar trend was observed in Hispanics but the number of samples was not sufficient (data not shown). However, there was no association between rs2476601 and the presence of lupus anticoagulant (LA) with negative or low titer aCL (P = 0.09). While not statistically significant, we observed an increase in the odds ratio in Europeans for the presence of lupus nephritis, or anti-dsDNA antibodies (1.49 and 1.47 respectively) for rs2476601.
