PRR4 and Down syndrome: On the contrary, females affected by Down syndrome showed lower values of CpG unit 3 in PRR4 amplicon compared to sex- and age-matched healthy controls (ANOVA p-value correcting for age: 6.2*10-5), while no significant differences were found between males affected by Down syndrome compared to sex- and age-matched controls (Figure 2B and 2D, Supplementary Figure 5).