How many CpG repeats must exist in an island for it to be considered a CpG island?

Question

Can the CG box promoter region be considered a CpG island?

Answer 1

The usual formal definition of a CpG island is a region with at least 200 bp and with a GC percentage that is greater than 50% and with an observed/expected CpG ratio that is greater than 60%.[3] Another recent study revised the rules of CpG island prediction in order to exclude other GC-rich genomic sequences such as Alu repeats. Based on an extensive search on the complete sequences of human chromosomes 21 and 22, DNA regions >500 bp with a GC content >55% and observed CpG/expected CpG of 0.65 were more likely to be the true CpG islands associated with the 5' regions of genes.[4]

I would not consider the CpG in a promoter region as CpG islands.