suitable DNA extraction and sample freezing for MSP - (Oct/22/2012 )

Hi every one!

I'm working on my thesis topic and I need to know some initial info about methylation analysis.
I was wondering if DNA extraction without commercial kits (eg. with laundry detergents) affects methylation status of the promoter?
and, does freezing my serum samples ( which I intend to get my DNA from it) changes the methylation pattern?

I'll really appreciate any recommendation and clues.

The answer to either of your question is NO. Freezing DNA won't change DNA methylation status. Commonly used DNA isolation methods do not affect it either. But if you are going to use the DNA to do bisulfite conversion for analyzing methylation, you do need pure DNA.