6.1.1 Preface: CpG islands It is known that due to biochemical considerations that CpG, the pair of nocleotides C and G, appearing successively, in this order, along one DNA starnd, is relatively rare in DNA sequences, excluding particular sub-sequences, which are several hundreds of nucleotides long, where the couple CpG is more frequent. These sub-sequences, called CpG islands, are known to a...