exception for promoter methylation-mediated silencing - (Jan/07/2005 )

A gene that I am working with shows promoter methylation (detected by both MSP and bisulfite sequencing) but I found that the mRNA of the gene is still expressed.

Does anyone know if there are exceptions for promoter methylation-mediated gene silencing?

How big is the area you have mapped using bisufite squencing? Have you covered the whole 5' CpG island of your gene? Usually, if a gene is expressed, there should be no methylation within the island, while methylation may exist outside of it.