C reactive protein-757T/C polymorphism and its relationship with serum C reactive protein levels in the patients with lone atrial fibrillation

Abstract

Objective To investigate the-757T/C polymorphism of C reactive protein (CRP) gene and its relationship with serum CRP levels in the patients with lone atrial fibrillation (LAF) . Methods Three hundred and forty-six subjects were enrolled in this study including 112 LAF (case group) , 98 AF with structure heart disease (intervention group) , and 136 healthy controls (control group) . The technique of polymerase chain reactiom-restriction fragment length polymorphism (PCR-RFLP) was used to identify-757T/C genotype of CRP. Meanwhile, serum levels of CRP were determined. Chi-square test and one-way ANOVA were used to assess the correlation between two groups. Results ① CRP-757T/C polymorphism distribution: The TT, TC and CC genotypes expressed in all groups.The TT genotype frequency was significantly increased in the case group compared to the intervention and control groups (76.79 vs. 50.00 vs. 38.24, P<0.001) . Pair comparison results showed that the TT genotype frequency was also significantly higher in case group compared to the control group (χ2=36.292, P<0.001) and the intervention group (χ2=13.294, P<0.001) . However, the CT genotype frequency was significantly lower in the case group compared to the other two groups (19.64 vs. 42.85 vs. 57.35, P<0.001) . Pair comparison results showed thatthe CT genotype frequency was significantly lower in case group, compared to the control group (χ2=36.982, P<0.001) and the intervention group (χ2=16.333, P<0.001) . The CC genotype frequency was comparable among the groups, but the rate of CC genotype in case group was less than that in the other two groups (3.57 vs. 7.14 vs. 4.41) . The frequency of T or C allele among the three groups showed that the T allele frequency in case groupwas higher than the other two groups (86.61 vs. 71.42 vs. 66.91, P<0.001) , and the C allele frequency in case groupwas much lower (13.09 vs. 28.57 vs. 33.09, P<0.001) . Pair comparison results showed that the C allele frequency was lower in case groupcompared to the control group (χ2=25.981, P<0.001) .②Comparison of serum CRP levels among three groups: the serum levels of CRP showed normal distribution (P=0.103) and were different (F=6.576, P=0.002) among three groups, the case group and the intervention grouphad a higher level of serum CRP than the control group (P=0.001, P=0.002, respectively) .The serum CRP concentration was similar in the case group and intervention group. ③The correlation between CRP-757T/C genotype and serum CRP level: in all subjects the serum CRP levels with CT+CC genotype were lower than those with TT genotype [ (1.381±0.401) mg/L vs. (1.570±0.325) mg/L, P=0.032] . The lower serum CRP levels were also found in subjects with CT+CC genotype compared to TT genotype in the intervention group [ (1.517±0.320) mg/L vs. (1.532±0.419) mg/L, P=0.047] . Conclusion The serum CRP level increased in AF patients. CRP-757C/T polymorphism was correlated with LAF and serum CRP levels. TT genotype mayincreasethe serum CRP levels and its frequency increased in patients with LAF. C allele may provide a protective effect and T allele may be a pathogeneticbasis of LAF. Key words: Atrial fibrillation; C reactive protein; Genes