Beyond the Human Genome Sequence: Duke Scientists Map "Silenced Genes"

Randy Jirtle, Ph.D. and Alexander J. Hartemink
Duke University
NIEHS Grants R01ES013053 and R01ES015165

NIEHS-supported scientist Randy Jirtle of Duke University has identified and mapped a set of about 200 genes that are turned off or silenced and are believed to play a profound role in people’s health. This work marks an important step in studying how the environment interacts with genes to help determine why some people get sick and others don’t.

Usually, people inherit two alleles or copies of genes, one from each parent. Typically, both copies are active, but if one copy of a gene becomes mutated and stops working properly, often the other copy can compensate. Genetic imprinting turns off or silences the backup copy. Molecular signals such as DNA methylation imprint the copy from the other parent to be silent. Until now, only about 40 human imprinted genes had been identified.
The research team reported that many of the newly found imprinted genes are in regions of chromosomes already linked to the development of obesity, diabetes, cancer and some other major diseases. One of the newly found identified genes appears to prevent bladder cancer. A second appears to play a role in causing various cancers and may affect epilepsy and bipolar disorder.

Previous research has indicated that imprinted genes accounted for only about 1 percent of the human genome. While scientists must confirm that the newly identified genes are truly silenced, the new map matches that tally.

Citation: Luedi PP, Dietrich FS, Weidman JR, Bosko JM, Jirtle RL, Hartemink AJ. Computational and experimental identification of novel human imprinted genes. Genome Res. 2007 Dec;17(12):1723-30.