Characterization of human epigenomes.

Histone modifications play a key role in regulating transcription and thus ultimately regulate cellular development and differentiation. To understand how histone modifications influence normal development and disease states, a global catalogue of histone modifications and modifying enzymes in normal and disease states is necessary. The first such systematic mapping experiments using the recently developed ChIP-Sequencing technique have revealed a combinatorial modification 'backbone' consisting of multiple histone modifications associated with active transcription. The human epigenomic datasets that are now being produced provide valuable resources for a better understanding of the functional regulatory elements of transcription and the pathways necessary for normal cellular development and pathological conditions.