A common way of studying methylation in cells is to sequence DNA samples before and after modification with sodium bisulfite. The sodium bisulfite deaminates Cytosine residues, generating Uracil residues, therefore resulting in a change in the sequence as compared to the non-modified DNA. Sodium bisulfite does not react with 5-methylcytosine so there will be no change in the sequence of those modified bases. When tumors are sequenced to study methylation patterns and epigenetic control, what would be the best control for sequencing using this technique?
A) Non-cancerous tissue DNA from a different individual but from the same organ
B) Liver DNA from the same individual that the cancer sample is from
C) DNA from non-cancerous tissue from the same individual's organ as the cancer
D) A combination of DNA from liver, brain and muscle from the same individual that has the cancer

Question

Quizplus · Accepted Answer

The best control for studying methylation patterns in tumors would be non-cancerous tissue DNA from the same organ as the cancer. This is because methylation patterns can vary between different tissues, so using DNA from the same individual's organ is the best way to control for this variable. Using DNA from a different individual or unrelated tissues (such as liver, brain and muscle) would not provide an accurate control.

A Common Way of Studying Methylation in Cells Is to Sequence