HLA-DRB1 and systemic lupus erythematosus: Although 14bp ins has been shown to be in strong LD with DRB1*03:01 [28, 35], the major risk allele for SLE in the Caucasian populations, DRB1*03:01 is very rare in the Japanese population (allele frequency 0.1% [29]), and cannot explain the association of 14bp ins.