PON2 and Parkinson disease: The greater prevalence and incidence of PD in males compared to females [36, 38] has been at least partly attributed to a sex difference in susceptibility of nigrostriatal DA neurons to oxidative stress, with the female sex hormone estradiol thought to convey this protection [12, 33] and which may involve maintenance of higher basal expression of PON2 protein in females [13, 25].