Figure 3. .

Chromosomal view of methylation variability by CpG island microarray analysis. A, Unmethylated fraction of genomic DNA extracted from sperm samples (n=21) hybridized individually (Cy5), in contrast to the pooled reference control (Cy3). The CV of the Cy5/Cy3 ratio was calculated for each spot across the 21 individuals and was mapped to the corresponding genomic location. Each chromosome ideogram is overlaid with red bars that represent the position of each clone on the CpG island microarray. The bars highlighted in green are the loci that showed variance in the 90th percentile (the top 10% of loci exhibiting the largest degree of DNA methylation variation). B, Screenshot of the custom annotation track on the UCSC Genome Browser (available from the Center for Addiction and Mental Health). Shown is chromosome 6, which includes the major histocompatibility complex locus that was screened for epigenetic variability by the Human Epigenome Project pilot study.⁸