Identification and properties of imprinted genes and their control elements

Imprinted genes have the unusual characteristic that the copy from one parent is destined to remain inactive. Though few in number they nonetheless constitute a functionally important part of the mammalian genome. With their memory of parental origin, imprinted genes represent an important model for the epigenetic regulation of gene function and will provide invaluable paradigms to test whether we can predict epigenetic state from DNA sequence. Since their first discovery, systematic screens and some good fortune have led to identification of over seventy imprinted genes in the mouse and human: recent microarray analysis may reveal many more. With a significant number of imprinted genes now identified and completion of key mammalian genome sequences, we are able systematically to examine the organization of imprinted loci, properties of their control elements and begin to recognize common themes in imprinted gene regulation.