Methylation detection in gDNA mixtures. (A) Female genomic DNA was diluted with male genomic DNA at ratios of 5:95, 10:90, 20:80, and 50:50. Two sets of mixtures were made and measured: M1 (male NA10923)/F1 (female NA10924) and M2 (male NA07033)/F2 (female NA06999). Methylation levels of six X chromosome-linked genes were calculated as the average of several (one to five) CpG sites for each gene. (B) Methylation profiles of individual CpG sites (only four are shown). Error bars represent the standard deviation of β-values calculated from four replicate experiments, done with the first set of mixtures (NA10923/NA10924).