This method allows for the identification of large regions of DNA with changes in methylation patterns through the use of methyl-CpG binding domain column which isolates methylated GC-rich sequences from both tumors and surrounding normal tissue. Subtractive hybridization is used subsequently, which removes sequences common to both, thereby leaving only methylated sequences unique to the tumor cells. Such a technique has numerous advantages and is easily one of the best methods to assess CpG islands for clinical studies.
S.Cross et al. Purification of CpG islands using a methylated DNA binding column. Nat. Genet. (1994) 6: 236-244.