Risk Genes and Anti‐C1q Autoantibodies in Upper Egyptian Patients With Systemic Lupus Erythromatosis—High Frequency of HLA‐DRB1*04:05–DQA1*03–DQB1*02 Risk Haplotype in Lupus Nephritis Patients

This study was performed to determine anti‐C1q serum level, genetic polymorphism in cytotoxic T lymphocyte–associated antigen 4 gene (CTLA‐4 gene) (rs 231775), and HLA class II genes in susceptibility and early prediction of systemic lupus erythematosus (SLE) and lupus nephritis (LN) in Upper Egyptian patients. A total of 60 unrelated cases of SLE (30 cases with LN) and 60 healthy controls were studied for HLA‐DQB1, HLA‐DQA1, and HLA‐DRB1 (DR4 subtypes) alleles. Anti‐C1q level was estimated by ELISA. CTLA‐4 gene genotypes were detected by PCR‐RFLP. The means of age of SLE patients without nephritis and LN patients were 24 ± 5.09 and 32 ± 7.26, respectively. Most of the patients were females (93.3%). Anti‐C1q serum level was significantly higher in LN patients (24.11 ± 4.26) versus SLE patients without nephritis (18.17 ± 1.35) ( p value < 0.001). The AA genotype of the CTLA‐4 gene was significantly higher in patients with LN versus SLE patients without nephritis (53.5% vs. 26.5%; p value = 0.035). (DR7)—DQA1*02‐DQB1*0303 haplotype was higher in SLE patients versus the control group and showed the highest odds ratio (7.37) with a significant p value (0.031). Odds ratios of DRB1*0405–DQA1*03–DQB1*0302 and DRB1*0405–DQA1*03–DQB1*02 were 6.263 and 4.214, respectively. DRB1*0405–DQA1*03–DQB1*02 haplotype was detected in 11.7% of LN patients versus 1.7% of SLE patients without nephritis (OR = 8.82, p value = 0.02). DRB1*0405–DQA1*03–DQB1*02 haplotype, in addition to CTLA‐4 gene (AA genotype), and high anti‐C1q serum level can predict the progression of SLE Upper Egyptian patients to LN.