The "Sixth Nucleotide" and it's epigenetic role in the brain

This is a really interesting article about the "sixth nucleotide" which was discovered about 2 years ago. Related to 5-methylcytosine (5-mc), 5-hydroxymethylcytosine (5-hmc) may have a different function in epigenetics as compared to it's derivative; specifically, it's been implicated in DNA methylation plasticity.

This study, coming out of Emory University, quantified 5-hmc in the brain (it's enriched compared to other tissues - at around 40%) and mapped 5-hmc genome-wide in mouse cerebellum and hippocampus cells from postnatal development through adulthood. 5-hmc seems to be enriched on active genes (in contrast to 5-mc), and regions controlled by 5-hmc revealed both stable and dynamically modified loci during the period of development and aging. The team is now focusing on mapping how 5-hmc changes during development and its relationship to neurological disorders such as Rett syndrome and autism.

You can read the synopsis on Science Daily.