X-chromosome tells the tale

March 16, 2005

HOUSTON - (March 17, 2005) - If the human genome is indeed the "book of life," then the X-chromosome is all plot.

In a report in today's issue of the journal Nature, a host of genome researchers describe the nature of this mysterious "chapter" in the DNA story.

"Large numbers of medically related genes happen to fall on the X," said Dr. Steven Scherer, associate professor in the Baylor College of Medicine department of molecular and human genetics and director of mapping in the BCM Human Genome Sequencing Center. "For a chromosome that is so bereft of genes compared to other chromosomes, this one is well characterized with regard to disease genes."

The fact that men have just one copy of the X chromosome makes the mutated genes on that one piece of DNA much easier to find, said Scherer.

Scherer and his colleagues in the BCM Sequencing Center were the number two contributors to the sequencing effort directed at the X chromosome. It was led by the Wellcome Trust Sanger Institute in Britain.

The story of each chromosome will be published eventually, with all the important features explained, said Scherer.

"I expect this chromosome is the all-star of the series. It will make interesting reading for the general scientific population and the lay public," he said. "If you were going to read a chromosome paper, this probably ought to be the one you read."

The role of the X and Y chromosomes have evolved. Before the split between birds and mammals, the X and Y chromosomes were just like any other pair of chromosomes - each was fairly similar and carried similar information.

The authors, in tracing the evolution of the X chromosome, showed that slowly, but surely, the Y chromosome "dropped off the face of the earth," said Scherer. "Although it contains a few important genes, it's almost like the appendix of the human genome."

Every woman has two X chromosomes. Each man has an X chromosome and a Y chromosome. In women, one of the X chromosomes is largely inactivated. Because there are actually few genes on the Y chromosome, inactivating most of one of the X chromosomes in women means that men and women each have one active X chromosome, where most of the coding information exists.

Among the most important actions of the Y chromosome is the determination of sex. In fact, the paper indicates that 10 percent of genes that cause production of proteins on the X produce genes most often expressed in the testis but that have increased activity in tumors of the testicles, melanoma and other cancers.

Over the past few years, the BCM sequencing center and others around the world have concentrated on sequencing the genomes of organisms studied in the laboratory. The future will look more closely at the human genome and its variations, said Scherer.

"The National Human Genome Research Institute is moving into a comprehensive program defining variations of all the genes in the genome," he said. That means looking at both normal subjects and patients with diseases.

"Papers like this one define the starting gate," said Scherer. "Now the research community is taking the next step. We are in a unique position at BCM of being in the largest clinical concentration in the world. We have more samples and examples of human disease right on our doorstep than most other centers. We mean to take that information, leverage and run with it. We hope this community will be the first to benefit from these kinds of advances."
-end-


Baylor College of Medicine

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.