More information from the methylome

Genetics is the study of DNA sequences. Until the last decade or so, those sequences were believed to be all important in understanding our biological destiny. Now it turns out that chemical changes to our DNA (most notably adding methyl groups) can have profound effects on our wellbeing without any underlying changes in nucleotide sequence. Those chemical changes make up the 'methylome', part of the burgeoning field of epigenetics.

Just as genomic studies required the data set of a few entire genomes, so too does epigenetics require having an epigenetic data base. An international consortium of researchers has just created a DNA methylation map from 1628 human samples, including 424 normal tissues, 1054 cancerous tissues of varying types, and 150 tissues with non-cancerous disorders. Already, these methylomes are producing significant results. For example, there are distinct differences between cancerous and non-cancerous tissues. Neurological and autoimmune diseases also have their own specific methylation profiles.

Besides adding to our understanding of the human condition, these data could have real medical benefits. Even without being able to ‘fix’ methylation so that tumors reverted to normal tissue profiles, the methylation data could help doctors determine the tissue of origin for metastatic tumors, always a plus when pursuing treatment options.