ABSTRACT
Alterations in the DNA methylation patterns of CpG (cytosine phosphoguanosine) dinucleotides, which are clustered in CpG islands, are very common in neoplastic cells.
These islands, approximately 29,000 in the human genome,
are very small stretches of DNA between 0.2 to 2 kb that are mostly found near the transcription start site of almost 60% of the promoters in human genes. They generally exist in an unmethylated state except for those genes located in inactive Xchromosomes of the female and/or silenced alleles of imprinted genes. The unmethylated status of CpG islands is very important in maintaining the transcriptional activity of genes that are expressed in tissue-specific manner.
