Chromosome X News and Research

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The X chromosome is one of the two sex chromosomes in humans (the other is the Y chromosome). The sex chromosomes form one of the 23 pairs of human chromosomes in each cell. The X chromosome spans about 155 million base pairs (the building blocks of DNA) and represents approximately 5 percent of the total DNA in cells.

Each person normally has one pair of sex chromosomes in each cell. Females have two X chromosomes, while males have one X and one Y chromosome. Early in embryonic development in females, one of the two X chromosomes is randomly and permanently inactivated in somatic cells (cells other than egg and sperm cells). This phenomenon is called X-inactivation or Lyonization. X-inactivation ensures that females, like males, have one functional copy of the X chromosome in each body cell. Because X-inactivation is random, in normal females the X chromosome inherited from the mother is active in some cells, and the X chromosome inherited from the father is active in other cells.

Some genes on the X chromosome escape X-inactivation. These genes are located at the tip of the short (p) arm of the X chromosome in an area known as the pseudoautosomal region. Although many genes are unique to the X or Y chromosome, genes in the pseudoautosomal region are present on both chromosomes. As a result, men and women each have two functional copies of these genes. Many genes in the pseudoautosomal region are essential for normal development.

Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. The X chromosome likely contains between 900 and 1,400 genes.

Genes on the X chromosome are among the estimated 20,000 to 25,000 total genes in the human genome.

Common genetic risk factor for multiple cancers identified

A study led by researchers at the Keck School of Medicine of the University of Southern California (USC) has found that one of seven genetic risk factors previously identified as increasing the probability of developing prostate cancer also increases the probability of developing colorectal cancer.

9 Jul 2007

Chromosome linked to colorectal cancer identified

Researchers at the Ontario Institute for Cancer Research and Cancer Care Ontario have successfully identified a specific genetic variation on chromosome 8 that is associated with colorectal cancer.

9 Jul 2007

Discovery of new gene with links to childhood asthma

New treatments for childhood asthma could be in the pipeline following the discovery of a gene associated with the condition.

5 Jul 2007

Breakthrough new asthma gene found

In a large-scale study conducted with 2,643 children, international researchers with the participation of the Department of Experimental Pneumology of Ruhr-University Bochum (RUB), Germany (Prof. Dr. Albrecht Bufe), have discovered a gene variant that contributes significantly to the risk of childhood asthma.

5 Jul 2007

Asthma gene found

A gene that is strongly associated with a risk of developing childhood onset asthma was identified by an international team of scientists, whose findings are published in the journal Nature.

4 Jul 2007

RNA molecules can orchestrate gene activity across vast portions of the human genome

Large, seemingly useless pieces of RNA - a molecule originally considered only a lowly messenger for DNA - play an important role in letting cells know where they are in the body and what they are supposed to become, researchers at Stanford University School of Medicine have discovered.

29 Jun 2007

Link between ciliary signaling and cancer

Submarines have periscopes. Insects have antennae. And increasingly, biologists are finding that most normal vertebrate cells have cilia, small hair-like structures that protrude like antennae into the surrounding environment to detect signals that control cell growth.

29 Jun 2007

Protein ATM prevents DNA damage from persisting through generations

A protein long known to be involved in protecting a cell from genetic damage has been found to play an even more important role in protecting the cell's offspring.

29 Jun 2007

Notch2 locus predicts prognosis in brain tumor patients

PLoS ONE has just published a study which defines a gene locus on chromosome 1 that predicts prognosis of brain tumor patients and may even set the basis for the development of more efficient drugs to combat brain cancer.

28 Jun 2007

Autism reversed in mice

Scientists in the United States have been able to reverse the effects of autism in specially bred mice.

26 Jun 2007

MIT researchers reverse behavioral symptoms in mice

Researchers at the Picower Institute for Learning and Memory at MIT have, for the first time, reversed symptoms of mental retardation and autism in mice.

26 Jun 2007

Mushrooms show promise for creation of new drugs

Mushrooms might serve as biofactories for the production of various beneficial human drugs, according to plant pathologists who have inserted new genes into mushrooms.

23 Jun 2007

Goltz syndrome gene found

Researchers funded in part by the National Institutes of Health have identified the gene that accounts for most cases of Goltz syndrome, a rare skin disorder that can also affect bone and eye development.

23 Jun 2007

Whitehead scientist to study key mechanism in cell division

"Cell division is one of the most fundamental aspects of biology, the process that makes life," says Iain Cheeseman, PhD. "And it has an intrinsic beauty."

22 Jun 2007

Noninvasive screening in early pregnancy reduces Down's births by 50 percent

Non-invasive screening of pregnant women with ultrasound early in pregnancy, combined with maternal blood analysis, has reduced the number of children born in Denmark with Down Syndrome by 50%, a scientist will tell the annual conference of the European Society of Human Genetics today.

19 Jun 2007