CD40 and systemic sclerosis: No evidence of association between CD40 polymorphisms and susceptibility to SSc was observed in the pooled analysis (allelic P value rs1883832: P = 0.61; OR, 1.02; 95% CI, 0.94 to 1.11; rs4810485: P = 0.42; OR, 1.04; 95% CI, 0.95 to 1.13; rs1535045: P = 0.275; OR, 0.95; 95% CI, 0.88 to 1.04).