Variations in the PON1, the paraoxonase 1 gene, have been linked to several medical conditions. Paraoxonases are esterases, a complex family of enzymes involved in breaking down chemicals including several types of pesticides and pharmaceutical drugs, and also involved in protecting both high- and low-density lipoproteins from oxidation. Individuals with less paraoxonase activity appear to be more susceptible to Heart disease, pesticide poisoning, atherosclerosis and Diabetes.
A second variation linked to cardiovascular disease, involving the potential of increased insulin resistance, is rs854560. This variation may be primarily a marker of a commonly co-inherited variation at the nearby "-108C/T" site, rs705379, located in the promoter of the paraoxonase gene [PMID 11335891].