To determine whether CR2 gene polymorphisms might contribute to the susceptibility of ONFH development in SLE patients of Korea (SLE_ONFH), the sample of 150 SLE and 50 SLE_ONFH Korean patients was genotyped using eight SNPs spanning a 39 kb region of the CR2 gene from 0.6 kb upstream to 2.8 kb downstream of the gene (Figure 1). Here, CR2 is linked to systemic lupus erythematosus.