C4A and systemic sclerosis: In fact, C4 eQTLs alone can explain more C4 expression variance than C4 CNs and C4 eQTLs are significant predictors for copy numbers of C4. We obtained 10,680 eQTLs of C4A and C4B from the GTEx v8 database and found that 37% of these are associated to SSc with pGWAS < 10−5 using the first dataset (Fig. 3a).