DNA methylation helps to maintain the large amount of non-coding DNA in an inert state. This is applicable to the DNA or genome of the organism, as well as any viral genes that are harbored within the cell. The methylation process prevents the transcription (the reading) of inserted viral sequences. One of the consequences of loss of methylation function is that it could cause the potentially harmful expression of these inserted viral genes. Under-methylation in normally silent regions of the DNA can cause the expression of inserted viral genes and may lead to autoimmunity or cancer.