Matrix metalloproteinases (MMPs) are capable of degrading extracellular matrix proteins, which are important determinants of arterial stiffness. This study aimed to test the hypothesis that MMP-3 and MMP-9 polymorphisms may modulate aortic stiffness and magnitude of aortic root dilation in patients after surgical repair of tetralogy of Fallot (TOF). We analyzed the MMP-3 promoter and MMP-9 -1562 C>T polymorphism in 79 TOF patients aged 19.9 ± 9.5 years and determined their associations with aortic stiffness and sinotubular dimension. Genotypic and allelic frequencies of MMP-3 for the 6A6A genotype and MMP-9 for the T allele did not differ between patients and published control data (all p>0.05). For the MMP-3 locus, patients with a 6A6A genotype and those with a 6A6A/5A6A genotype had similar aortic stiffness (p=0.60), heart-femoral pulse wave velocity (p=0.63), and z score of sinotubular junction (p=0.81). For the MMP-9 locus, the -1562T allele carriers had significantly lower aortic stiffness (p=0.005), slower heart-femoral pulse wave velocity (p=0.03), and smaller z score of sinotubular junction (p=0.047). Multivariate linear regression identified MMP-9 polymorphism (β=-0.31, p=0.005) as a significant correlate of aortic stiffness after adjustments for age at study, age at operation, sex, body mass index, systolic and diastolic blood pressures, and MMP-3 polymorphism. In conclusion, MMP-9 but not MMP-3 polymorphism exerts a modulating influence on aortic stiffness and aortic root dilation in patients after TOF repair.
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