To directly assess CpG methylation within an important lymphocyte subset, we next prepared genomic DNA from T-cells immuno-purified from PBL of 12 individuals with DS and 15 control individuals, and measured SUMO3, CD3Z and SH3BP2 promoter methylation, as well as methylation of the TMEM131 internal promoter region, by MS-Pyroseq. Here, TMEM131 is linked to Dravet syndrome.