So far, the approach to the epigenome has been somewhat piecemeal, with disparate groups cataloguing just the modifications in their cells or organisms of interest. Technological advances that allow faster and cheaper mapping of epigenetic modifications are now helping to unite these efforts.

The Human Epigenome Project, for example, was established in 1999, when researchers in Europe teamed up to identify, catalogue and interpret genome-wide DNA methylation patterns in human genes. The project is a collaboration between the Wellcome Trust Sanger Institute in Hinxton, UK, the National Centre for Genotyping near Paris, France, and the German company Epigenomics in Berlin. The consortium completed a pilot study of methylation patterns within the major histocompatibility complex followed by a more thorough analysis of the methylation patterns on three chromosomes. After showing the feasibility of such an approach “the consortium has decided to leave it to others to continue the endeavour”, says Achim Plum, senior vice-president for corporate development at Epigenomics.

ENCODE, or the Encyclopedia of DNA Elements, was launched in September 2003 by the US National Human Genome Research Institute (NHGRI) in Bethesda, Maryland. The project aims to identify all the functional elements in the human genome sequence. Following initial success, the NHGRI last October pledged $80 million over four years to scale up the project. Many of the functional elements so far identified by ENCODE are being studied for changes in methylation under a range of conditions.

The Epigenome Network of Excellence, headed by Thomas Jenuwein of the Research Institute of Molecular Pathology in Vienna, Austria, brings together 81 laboratories from 10 European countries under a €12.5-million (US$19.7-million) grant from the European Union to advance epigenetic research over the next five years. The network, which officially began in June 2004, supports members and non-members so that they can attend conferences, workshops and training visits, as well as offering them shared resources.

The US American Association for Cancer Research is championing the formation of the Alliance for the Human Epigenome and Disease (AHEAD) project. Under the leadership of Peter Jones, director of the University of Southern California's Norris Comprehensive Cancer Center in Los Angeles, AHEAD would coordinate an international interdisciplinary project to map a defined subset of epigenetic markers in a limited number of human tissues at different stages of development (see page 711). This would provide a reference epigenome to which samples from various diseases could be compared. The alliance would also try to develop a bioinformatics infrastructure to support the collection of epigenomic data.

AHEAD's planned efforts will be helped by January's announcement from the National Institutes of Health that it will invest more than $190 million over the next five years to accelerate epigenomics research. Grant applications are now being accepted for epigenome mapping centres, epigenomics data analysis and coordination, and technology development.

L.B.