Article: Rule-Breaker Genes Identified
- From: "Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx>
- Date: Sun, 2 Dec 2007 14:52:35 -0500 (EST)
Rule-Breaker Genes Identified
By Elizabeth Pennisi
ScienceNOW Daily News
30 November 2007
The battle of the sexes extends all the way to our chromosomes. In some
cases, the copy of a gene inherited from one parent shuts down, leaving just
the copy from the other parent active and upsetting the classic rules of
inheritance. Now researchers have come up with the first comprehensive map
of these so-called imprinted genes in humans. Many of them lie in regions of
chromosomes implicated in disease and may be involved in problems such as
autism and obesity.
Geneticists discovered imprinting in 1991 and now know that defects in
imprinted genes lead to abnormal development and to diseases such as
Angelman and Prader-Willi syndromes, both characterized by mental
retardation. Imprinting involves chemical modification of the relevant DNA,
alterations that can be strengthened or undone by diet, toxicants, or other
environmental factors. But imprinted genes have been hard to find because
imprinting can occur in just one tissue, whereas in the rest of the body,
two copies are active, making the gene appear normal. Indeed, until now,
geneticists knew of only 40 such genes.
To track down more, geneticist Randy Jirtle of Duke University in Durham,
North Carolina, enlisted Duke computer scientist Alexander Hartemink and his
graduate student Philippe Luedi to develop a computer program that can
learn. It improved its search ability by distilling common features of known
imprinted genes and contrasting them with characteristics of 552 genes that
are never imprinted. One difference is in the distribution of bits of
repetitive DNA that bulk up the genome near the gene in question, for
example.
Jirtle and colleagues used that program, along with commercially available
software as a further check, to scan the human genome. The software
predicted the existence of 156 more imprinted genes among the 20,770 human
genes. More than one-third of the genes function in development. Several
chromosomal regions have relatively high concentrations of these genes, the
researchers report online 30 November in Genome Research. One such region,
on chromosome 11, has quite a few: two previously known imprinted genes and
five unrecognized ones, including a gene possibly involved in lung cancer.
In the lab, the group confirmed that two genes on the list were imprinted as
predicted, boosting Jirtle's confidence in the software. Located on
chromosome 8, both are associated with cancer, and one, which is expressed
in the brain, is implicated in epilepsy.
Geneticist Benjamin Tycko of Columbia University cautions that more of the
predicted genes need to be verified as truly imprinted. But no matter what,
says quantitative geneticist Jason Wolf of the University of Manchester,
U.K., the map "is an important starting point for studies of gene expression
and gene functions. It will provide a valuable database for human
geneticists."
Source: Science
http://sciencenow.sciencemag.org/cgi/content/full/2007/1130/1?etoc
Posted by
Robert Karl Stonjek
.
- Prev by Date: Re: Article: Group selection, a theory whose time has come...again
- Next by Date: Re: Article: Group selection, a theory whose time has come...again
- Previous by thread: Re: Article: Group selection, a theory whose time has come...again
- Next by thread: Biomarkers in earth history
- Index(es):
Relevant Pages
|
