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.

Researchers discover new gene responsible for Brugada syndrome

Researchers at the University of Pittsburgh School of Medicine have identified a new gene responsible for a rare, inherited form of sudden cardiac arrest, known as Brugada syndrome.

1 Nov 2007

Discovery of gene variant linked to prostate cancer in African Americans

Researchers report a newly identified genetic variation that is linked to higher incidence of prostate cancer in African American men.

1 Nov 2007

New genetic variant associated with prostate cancer in African-Americans

Two tiny genetic variations may provide the best clues yet for finding more precise ways to estimate prostate cancer risk and improve screening and early detection for men of African descent, report researchers from the University of Chicago and the Translational Genomics Research Institute, Phoenix, AZ, in the December 2007 issue of Genome Research, published early online.

1 Nov 2007

Tasigna gets the green light in the U.S. to treat Chronic Myeloid Leukemia

The Food and Drug Administration (FDA) in the U.S. has given approval for a new drug to treat chronic myeloid leukemia (CML).

30 Oct 2007

Discovery of new peptide communication factor in bacteria

Discovery by Hebrew University of Jerusalem researchers of a new communication factor that enables bacteria to "talk to each other" and causes their death could have significant consequences leading to development of a new class of antibiotic medications.

29 Oct 2007

New egg-specific gene, JY-1 offers clues to infertility

A newly identified gene that controls embryo development in cows may someday offer clues into the cause of infertility in women.

29 Oct 2007

Obesity-related hormone is higher in children with Down syndrome

Children with Down syndrome are more likely than their unaffected siblings to have higher levels of a hormone associated with obesity, according to pediatric researchers.

28 Oct 2007

Test gives insight into prognosis in patients with plasma cell malignancies

A new Mayo Clinic study due to be presented at the annual meeting of the American Society of Human Genetics in San Diego this week shows that a chromosome test called “FISH” is better than conventional methods in identifying chromosomal genetic abnormalities associated with plasma cell malignancies.

24 Oct 2007

Researchers find crucial signal that switches on eye development

Researchers at the University of Warwick, funded by Wellcome Trust, have uncovered a crucial signal that switches on eye development.

24 Oct 2007

Advances in drug screening

With the discovery of suitable molecular targets - cellular molecules along pathways crucial for sustaining the life of cancer cells - comes the perplexing dilemma of where to find the next therapeutics that will bind to and disable those targets.

23 Oct 2007

Researchers discover genes linking stress, high blood pressure, alcoholism and tobacco addiction

A team led by a Heart and Stroke Foundation researcher has uncovered a series of genes linking mental stress, high blood pressure, alcoholism and tobacco addiction.

22 Oct 2007

Syngenta licenses chromatin gene stacking technology

Syngenta Biotechnology Inc. has announced that it has entered into a research and commercial license agreement for Chromatin's proprietary gene stacking technology.

22 Oct 2007

Chromatin licenses gene stacking technology to Syngenta Biotechnology

Chromatin Inc. has announced that it has entered into a research and commercial license agreement with Syngenta Biotechnology Inc. for Chromatin's proprietary gene stacking technology.

22 Oct 2007

New explanation for evolutionary changes in genetic sex-determination systems

In animals with separate sexes, embryos commit to becoming male or female at an early stage.

22 Oct 2007

Transgenics sped up

A new method of constructing artificial plant chromosomes from small rings of naturally occurring plant DNA can be used to transport multiple genes at once into embryonic plants where they are expressed, duplicated as plant cells divide, and passed on to the next generation -- a long-term goal for those interested in improving agricultural productivity.

19 Oct 2007

Oral medication restores missing protein in boys with muscular dystrophy

PTC124, an oral medication that changes the way muscle cells interpret genetic information, holds promise as a treatment for some patients with Duchenne muscular dystrophy (DMD), the Muscular Dystrophy Association ( http://www.mda.org/ ) announced today.

19 Oct 2007