CRP and SAA1 Haplotypes Are Associated with Both C-Reactive Protein and Serum Amyloid A Levels: Role of Suppression Effects

Figure 2

A three-variable mediation model: SAA and CRP levels as a mediator of the association between the SAA and CRP genotypes/haplotypes and CRP and SAA levels. Linear regression models were used to assess the following path associations: in Figure 1(a): () relationship between the SAA genotype and SAA level, () relationship between SAA level and CRP level, () relationship between the SAA genotype and CRP level, and () relationship between the SAA genotype and CRP level after adjustment for SAA levels. Each estimate along the path represents the unstandardized β coefficient from the regression model. The results indicate that, after adjustment for SAA levels, the SAA genotypes exhibited a stronger association with CRP level. The direct effects () of the SAA genotypes on the CRP level (0.017) were greater than the total effects () (−0.002) and revealed similar magnitudes and opposite signs than those of the mediation effects () (−0.018), suggesting significant mediation (suppression) by the SAA levels. All of the models were adjusted for age, sex, BMI, current smoking status, and medications for hypertension, diabetes mellitus, and dyslipidemia. . In addition, the other analysis exhibited similar suppression effects ((b), (c), (d), and (e)). ^#SAA genotypes.

(a)

(b)

(c)

(d)

(e)