Examples of HpaII-McrBC PCR assays for CpG islands on human Chromosome 21. The results of self-Harr plot and HpaII-McrBC PCR were depicted for (A) a completely methylated CGI #123, (B) an unmethylated CGI #114, (C) a compositely methylated CGI #112, and (D) an incompletely methylated CGI #106. In the self-Harr-plot, each CGI is indicated asan open square and the regionsflanking the island (500 bp on both sides) are shaded. Oblique lines running in parallel with the diagonal line indicate the tandem repeat sequence. The PCR products from mock-treated (lane 1), HpaII-digested (lane 2), MspI-digested (lane 3), and McrBC-digested DNAs (lane 4) were electrophoresed, stained with ethidium bromide, and visualized by UV illumination. The part where the diagonal line isnot shown indicatesthe position of interspersed repeats, which were masked by RepeatMasker.
