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.

Molecule that helps DNA replicate may make good target for cancer therapy

In order to divide, cells must first replicate their chromosomes. Cells use an array of proteins to accomplish the job, including a large enzyme complex that synthesizes new strands of DNA.

21 Oct 2004

Discovery of the gene for a form of Joubert Syndrome

Researchers at the University of California, San Diego (UCSD) School of Medicine have discovered the gene for a form of Joubert Syndrome, a condition present before birth that affects an area of the brain controlling balance and coordination in about 1 in 10,000 individuals.

21 Oct 2004

Researchers trim count of human genes to 20,000-25,000

Scientific description of the finished human genome sequence, reducing the estimated number of human protein-coding genes from 35,000 to only 20,000-25,000, a surprisingly low number for our species.

21 Oct 2004

Scientists have devised a novel way to repair one of the genetic mutations that causes ataxia-telangiectasia

UCLA scientists have devised a novel way to repair one of the genetic mutations that causes ataxia-telangiectasia, (A-T), a life-shortening disorder that devastates the neurological and immune systems of one in 40,000 young children.

19 Oct 2004

Comprehensive study raises questions about "demethylation" agents

Agents believed to selectively "restart" genes that limit cancer's growth -- a potential treatment option already in early clinical studies -- instead turn off as many genes as they turn on, a team of researchers from the National Cancer Institute and Johns Hopkins has discovered.

18 Oct 2004

Technique for genetically modifying blood stem cells brings cure for blood diseases closer

The condition of mice with a genetic blood disease called beta-thalassemia improved significantly following treatment of their blood forming cells with a gene that enabled them to produce the type of hemoglobin normally found only in the fetus.

12 Oct 2004

Combination of computer science and biology could aid cancer research

The technique helps to show how cells modify their own genetic makeup and may allow cancer treatments to be tailored more precisely to a patient's disease.

11 Oct 2004

New targets for combating infections in medical implants

Navarre researcher, Jaione Valle Turrillas, has identified two genes that could help as targets for pharmaceutical drugs that fight the Staphylococcus aureus bacteria - one of the bacteria which causes most infections in medical implants.

8 Oct 2004

Fourth gene found for distal muscular dystrophy

MDA grantees Peter Hedera, a neurologist at Vanderbilt University in Nashville, Tenn., and Nigel Laing, a molecular biologist at the University of Western Australia, were part of a team that identified a fourth gene that, when flawed, leads to distal muscular dystrophy (DD).

4 Oct 2004

Researcher looks for clues to degenerative, deadly disease called Ataxia-telangiectasia

Few have heard of the degenerative, deadly disease called Ataxia-telangiectasia (A-T) but a University of Alberta researcher is hoping to provide clues to this mysterious disorder.

23 Sep 2004

Edible vaccine for HIV AIDS

Scientists from Novosibirsk are engaged in the development of an unusual vaccine which, apart from being less expensive to produce, safe and painless to administer, is also edible.

22 Sep 2004

Experimental drug PKC412 may be the key to treating myeloproliferative disease

Scientists at Dana-Farber Cancer Institute and Brigham and Women's Hospital have prolonged the lives of mice with a rare blood disorder by using an experimental drug that blocks signals promoting runaway growth of blood cells.

21 Sep 2004

Novel strategy for stimulating the production of utrophin

Researchers at the University of Pennsylvania School of Medicine report a novel strategy for stimulating the production of utrophin – an important muscle protein in young mice – for muscular dystrophy therapy.

21 Sep 2004

Research may provide a better understanding of the mental retardation observed in Cri-du-Chat Syndrome

By specifically deleting the adhesion protein d-catenin, which is found exclusively in the brain, researchers at UCLA have found evidence that loss of d-catenin produces severe cognitive and synaptic dysfunction.

20 Sep 2004

New insights into ancient mating and migration patterns in humans

Men have been tomcatting around since time immemorial, and some traveled far from home to do it, new research suggests.

20 Sep 2004

Newly completed Chromosome 5 sequence will be a powerful tool for scientists trying to understand human disease

Four years after publicly revealing the official draft human genetic sequence, researchers have reached the halfway point in dotting the i's and crossing the t's of the genetic sentences describing how to build a human.

16 Sep 2004

New genetic test can predict cleft lip or palate

Researchers have developed a new genetic test that can help predict whether parents who have one child with the "isolated" form of cleft lip or palate are likely to have a second child with the same birth defect. Isolated clefts account for 70 percent of all cleft lip and palate cases.

10 Sep 2004

Suprising new information on the HOX genes

Researchers at the University of Bergen are now able to present new information on the HOX genes – the “software” to design animals. The findings are published in today’s issue of Nature.

10 Sep 2004

Childhood leukaemia significantly lower in Asia than in Western countries

The incidence of childhood leukaemia in Britain increased dramatically during the twentieth century. The increase has mainly affected the under-five age group, in whom the risk increased by more than 50 per cent during the second half of the century alone.

9 Sep 2004

Gene linked to both alcoholism and depression

A national team of investigators led by psychiatric geneticists at Washington University School of Medicine in St. Louis has identified a gene that appears to be linked to both alcoholism and depression.

8 Sep 2004