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CpG Islands

Meaning

CpG Islands are specific genomic regions characterized by a high frequency of cytosine-guanine (CpG) dinucleotides, where a cytosine nucleotide is immediately followed by a guanine nucleotide in the DNA sequence. These segments are typically found in the promoter regions of approximately 60-70% of human genes, serving as critical regulatory elements for gene expression. In healthy cells, the cytosines within these islands are predominantly unmethylated, which is crucial for maintaining proper cellular function.