CpG islands and start sites - (Dec/19/2005 )

At the 5' end of a gene we find a promoter and often a CpG island. My question is, how far upstream from the first exon is this CpG island usually located, and what is its typical length?

Thanks in advance

If you really want to dig into this question, read this classic paper describing CpG islands.
http://www.ncbi.nlm.nih.gov/entrez/query.f...7&dopt=Citation

And also this one:
Comprehensive analysis of CpG islands in human chromosomes 21 and 22.
http://www.ncbi.nlm.nih.gov/entrez/query.f...1299&query_hl=4