To estimate the frequency in the association of CpG islands with genes distributed in human genome, we have screened the statistically expected CpG islands for sequenced human DNAs compiled in DNA database. The survey of 2605 genomic sequences (>300 bp) coding 833 genes mapped on human chromosomes identified 1030 CpG island-linked sequences classified to 324 genes, indicating that at least 39% of human genes are coincided with CpG islands. Furthermore, it is found that 19%, 36% and 45% of CpG islands mapped on single chromosomal bands are located on G-, R- and T-bands. This result suggests that the occurrence of CpG island-genes increases with increasing the global G+C% level of chromosomal bands.
