PON1 and metabolic syndrome: A statistically significant influence on PON1 concentration was observed for the family history of cardiovascular disease (p < 0.001), metabolic syndrome (p < 0.001), hypertension (p = 0.004), pre-diabetes (p = 0.004), and L55M polymorphism (p = 0.015), most particularly for the LM + MM variants (p = 0.004).