HLA-DRA and systemic lupus erythematosus: The five others SNPs in C3 are nearby HLA-DQA, HLA-DRA (2 SNPs), BTNL2 and HCG23. The only SNP (rs2247056) found in C4, also common with C1, is located in intron 1 of the LINC02571 gene and was previously associated with a risk for developing SLE.