Copy number variations of <italic>HLA-DRB5</italic> is associated with systemic lupus erythematosus risk in Chinese Han population

Systemic lupus erythematosus (SLE) is a polygenic, systemic, autoimmune disease. Copy number variants (CNVS) have been discovered to be associated with a number of complex disorders. We undertook the current study to explore the potential associations between genomic CNVS and SLE in Chinese Han population. In the discovery stage, seven SLE patients were examined with the high-density comparative genomic hybridization microarrays in the screening test for SLE associated CNVS. Then, in the validation stage, 135 SLE patients and 219 matched healthy subjects were investigated for the CNVS of gene HLA-DRB5 by AccuCopy™ technology. Quantitative polymerase chain reaction was carried out to determine the copy number (CN) and mRNA level of HLA-DRB5 in SLE patients. Although the mRNA level of HLA-DRB5 between the CN deletion group and the CN normal group in SLE patients was not statistically positive (P = 0.46), our results still showed more CN of HLA-DRB5 in SLE patients than in healthy controls (P = 3.98 × 10(-6)). Odds ratio for CN deletion was 0.38 (95% confidence interval (CI), 0.23-0.61, P = 7.79 × 10(-5)) and for CN duplication was 1.89 (95% CI, 0.56-7.66, P = 0.37), respectively. These findings indicated that CNVS of HLA-DRB5 was associated with the risk of SLE, and CN deletion appeared to be protective for SLE.