BackgroundAlthough many conventional factors have been associated with the development of arterial aging, cardiovascular diseases remain the first cause of death in old age. Therefore, identification of new risk factors may prove promising for monitoring this serious health problem. Oxidative stress and particularly catalase (CAT), an antioxidant enzyme, play an important role in endothelial cell pathophysiology, in shear stress response and ultimately in arterial aging.ObjectiveExamine the relationships between CAT haplotypes and phenotypes of arterial aging (mean internal diameter, mean intima–media thickness of the common carotid arteries (CCA), presence of atheromatous plaques) in two French cohorts.Methods and results564 middle-aged French individuals (mean age 53 ± 12 years) from two cohorts (ERA and STANISLAS cohorts) were included in the study. Blood pressure, CCA intima–media thickness, CCA internal diameter and number of atheromatous plaques were measured. Catalase rs769214 SNP genotyping was performed. We identified a CAT haplotype that influences arterial aging. Individuals carrying the CAT2 haplotype had a higher mean internal diameter of CCA with aging and/or with an SBP ≥140 mmHg and were associated with a greater number of atheromatous plaques than CAT1 haplotypes carriers. This CAT2 haplotype appeared as an independent risk factor of arterial aging, similarly to previously identified factors such as age, systolic blood pressure, male, sex, tobacco use, hs-CRP, BMI and diabetes.ConclusionThe present study highlights the roles of CAT haplotypes in arterial aging and underlines the beneficial impact of the CAT1 haplotype on mean internal diameter of the CCA and atheromatous plaque number as well as on potential associated diseases.