FMR1 and fragile X syndrome: Pretto et al. [46] studied 18 patients with FXS (9 with FXS + ASD), including 7 with size- and 6 with methylation-mosaicism, demonstrating that FMR1 RNA and FMRP levels correlated in general with FMR1 methylation in peripheral blood cells and fibroblasts although there were differences in CGG expansion and blood samples showed lower methylation.