# What is transcription aberrancy?

## "Moreover, epigenetic memory in iPSCs also reflects in insufficient DNA methylation on somatic-specific gene loci, and such a hypomethylated state is usually associated with transcription aberrancy." Ohi Y, Qin H, Hong C, et al. Incomplete DNA methylation underlies a transcriptional memory of somatic cells in human iPS cells. Nat Cell Biol 2011; 13:541-549

Sep 16, 2016

Abnormal transcription levels (unbalanced)

#### Explanation:

In this context 'transcription aberrancy' means that there is something wrong with the levels of transcription.

Methylation of DNA is a mechanism cells use to regulate the transcription of genes:

• hypermethylated DNA: lot of methyl groups on the DNA = strong interaction with DNA-associated proteins (histones) $\to$ compact DNA that is not (easily) transcribed.
• hypomethylated DNA: few methyl groups on the DNA = weak interaction with histones $\to$ loose DNA that is easily transcribed.

In this case the induced pluripotent stem cells (iPSC's) are found to have lower levels of methylation than embryonic stem cells (ESC's). This can be a problem because it leads to higher transcriptional activity as is also observed in cancer. This higher level of transcription is what they call $\textcolor{red}{\text{transcriptional aberrancy}}$.