Objective: To observe whether single nucleotide polymorphisms (SNPs) within the OLF1/EBF-associated zinc finger protein (OAZ) gene are associated with lupus nephritis (LN) susceptibility in Chinese population.
Methods: Eight SNPs located around the positive microsatellite marker D16S517 within OAZ gene with relatively high heterozygosity were chosen for genotyping on 184 systemic lupus erythromatosus (SLE) patients, including 101 non-LN patients and 83 LN patients, and 286 normal controls using TaqMan MGB allelic discrimination method. Data were collected by SDS 2.0 software. Haplotypes and their frequencies were constructed and estimated, and linkage disequilibrium analysis between pairs of SNPs was evaluated by calculating the D Prime using Helixtree program. Case-control study was performed between the SLE, LN, and non-LN groups and normal control group.
Results: (1) The frequency of SNP rs1344531 T allele was 47.0% in the SLE patients, significantly higher than that in the controls [38.1%,; chi(2) = 7.300, P = 0.008, OR (95% CI) = 1.441 (1.105 - 1.878)], which showed that the frequency of SNP rs1344531 T allele is associated with SLE susceptibility. The genotypic distribution of SNP rs1344531(CC/CT/TT) differed significantly between the SLE patients (25.5%/54.9%/19.6%) and normal controls (38.1%/47.6%/14.3%) (chi(2) = 8.394, P = 0.015). The CC genotype frequency of the SLE patients was 25.5%, significantly lower than that of the normal controls [38.1%; chi(2) = 7.976, P = 0.005, OR (95% CI) = 0.557 (0.370 - 0.838)] (2) The SNP rs1344531 T allele frequency of the SLE patients was 53.0%, significantly higher than that of the normal controls [38.1%; chi(2) = 11.769, P = 0.001, OR (95% CI) = 1.832 (1.293 - 2.596)], which showed an associated between SNP rs1344531 T allele frequency and LN susceptibility. The genotypic distribution of SNP rs1344531 (CC/CT/TT) differed significantly between the LN patients (22.9%/48.2%/28.9%) and the normal controls (38.1%/47.6%/14.3%) (chi(2) = 12.065, P = 0.002). The CC genotype frequency of the LN patients was 22.9%, significantly lower than that of the normal controls (38.1%) [chi(2) = 6.578, P = 0.013, OR (95% CI) = 0.481 (0.274 - 0.848)]. The TT genotype frequency of the LN patients was 28.9%, significantly higher than that of the normal controls (14.3%) [chi(2) = 9.423, P = 0.003, OR (95% CI) = 2.431 (1.363 - 4.334)]. No statistical significance was observed between the non-LN patients and normal controls in TT genotype frequency. (3) The frequencies of haplotypes containing rs1344531:rs1420676-rs1344531(C-T) [chi(2) = 11.731, P = 0.001, OR (95% CI) = 1.867 (1.302 - 2.676)], rs3803665-rs1420676-rs1344531(C-C-T) [chi(2) = 8.876, P = 0.004, OR (95% CI) = 1.772 (1.213 - 2.589)], and rs2292155-rs3803665-rs1420676-rs1344531(C-C-C-T) [chi(2) = 9.962, P = 0.002, OR (95% CI) = 1.915 (1.274 - 2.880)] were all significantly higher in the LN patients in comparison with the normal control group (41.0% versus 27.1%; 33.3% versus 21.8%; and 27.0% versus 16.2%); while the frequencies of other haplotypes: rs1344531-rs2080353(C-A) [chi(2) = 8.06, P = 0.005, OR (95% CI) = 0.603 (0.424 - 0.856)], rs1344531-rs2080353-rs933564 (C-A-G) [chi(2) = 7.929, P = 0.006, OR (95% CI) = 0.602 (0.422 - 0.859)] were significantly lower than those of the normal control group (39.5% versus 52.2%, and 36.6% versus 49.2%), which produced additional support for such association.
Conclusion: SNP rs1344531 and some haplotypes containing SNP rs1344531 within OAZ are significantly associated with LN susceptibility. Genetic variants of the OAZ gene are involved in the pathogenesis of LN.