Low apolipoprotein M serum levels correlate with Systemic lupus erythematosus disease activity and apolipoprotein M gene polymorphisms with Lupus
OBJECTIVE To examine whether the apolipoprotein M (APOM) rs805297 G/T polymorphism is associated with risk of rheumatoid arthritis (RA) in a Chinese population. METHODS We studied APOM rs805297 G/T gene polymorphism in 520 RA patients, and 520 controls in a Chinese population. Genotyping was done by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The blood plasma concentration of APOM was measured by an enzyme-linked immunosorbent assay in 84 RA patients and 84 controls. RESULTS When the APOM rs805297 G/T GG homozygote genotype was used as the reference group, the TT or GT/TT genotype was associated with an increased risk for RA (TT vs. GG, adjusted odds ratio 1.76, 95% CI 1.11-2.77, P=0.016; GT + TT vs. GG, adjusted odds ratio 1.30, 95% CI 1.02-1.67, P=0.037). The average concentration of APOM in plasma was significantly higher in RA patients compared to controls. Stratification analysis found a significantly increased risk for RA associated with the APOM rs805297 TT genotype among male patients, C-reactive protein (CRP)-positive patients, anticitrullinated protein/peptide antibodies (ACPA) - positive patients, rheumatoid factor (RF) - positive patients, patients with higher levels of the erythrocyte sedimentation rate (ESR), patients with higher DAS28 score and patients with higher functional class compared to the APOM rs805297 GG genotype. CONCLUSION These findings suggest that the functional single-nucleotide polymorphism APOM rs805297 G/T variant allele was associated with RA risk.