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.

Gene mutation may increase the risk of prostate cancer up to three times in African-American

Researchers have identified a gene mutation that may increase the risk of prostate cancer up to three times in African-American men with a family history of the disease.

20 Sep 2005

Suppression of FOXO1a gene might kill resistant alveolar rhabdomyosarcoma (ARMS) tumors

FOXO1a caused death of tumor cells in laboratory study by triggering expression of caspase-3, which blocks cell division and causes cells to undergo apoptosis, according to St. Jude.

20 Sep 2005

Acute-leukemia sign may signal need for different therapy

A type of chromosome change that was thought to predict a good response to treatment in patients with acute myeloid leukemia (AML) might actually signal the need for a different therapy to achieve the best outcome.

19 Sep 2005

Nitric oxide could one day help women in their 30s and 40s remain fertile longer

Researchers have found that an important chemical compound, nitric oxide, appears to slow or reverse the aging of eggs in mouse ovaries. The finding suggests nitric oxide could one day help women in their 30s and 40s remain fertile longer and increase their chances of having healthy babies, the scientists say.

7 Sep 2005

Significant advance in the study of small ribonucleic acids

Scientists from the University of Delaware have made a significant advance in the study of small ribonucleic acids (RNAs), discovering 10 times more small RNAs in the plant Arabidopsis than previously had been identified. The advance is reported in the Sept. 2 issue of Science magazine.

5 Sep 2005

Overall genome landscape between chimps and humans can be attributed to large segmental duplications

A study comparing the genomes of both humans and chimpanzees has found that much of the genetic difference between the two species came about in events called segmental duplications, in which segments of genetic code are copied many times in the genome.

4 Sep 2005

Significant advance in the study of small ribonucleic acids

1 Sep 2005

Toluidine blue dye reveals oral cancers

A team of Canadian scientists may have discovered a way to use a simple dye as a litmus test to identify abnormal areas of the mouth that may become cancers.

1 Sep 2005

Human Y chromosome stays intact while chimp Y loses genes

The human and the chimpanzee Y chromosomes went their separate ways approximately 6 million years ago. But ever since this evolutionary parting, these two chromosomes have experienced different fates, new research indicates.

1 Sep 2005

Compound called GRN163L blocks lung cancer

Researchers at UT Southwestern Medical Center have found a compound that shows promise as a way to block the spread, or metastasis, of lung cancer.

1 Sep 2005

Discovery of a potential oncogene in ovarian cancer

Researchers at The University of Texas M. D. Anderson Cancer Center report they have discovered a potential oncogene in ovarian cancer, which is the leading cause of gynecological cancer death in U.S. women.

22 Aug 2005

First proof of how the rare disorder Fanconi anemia causes chromosomal instability

The scientists found a gene mutation not previously known to be related to Fanconi anemia, and they say that BRIP1 is the first gene associated with the disease whose protein has a known function.

22 Aug 2005

Researchers have discovered a gene linked to age-related maculopathy

University of Pittsburgh researchers have discovered a gene linked to age-related maculopathy (ARM), the leading cause of untreatable blindness in the elderly. Their discovery suggests a simple test might be able to identify those at risk for what is commonly known as macular degeneration (AMD) and may lead to the development of more effective preventive strategies.

16 Aug 2005

Placental tissue could feasibly provide an abundant source of cells with the same potential to treat diseases as embryonic stem cells

Routinely discarded as medical waste, placental tissue could feasibly provide an abundant source of cells with the same potential to treat diseases and regenerate tissues as their more controversial counterparts, embryonic stem cells, suggests a University of Pittsburgh study to be published in the journal Stem Cells and available now as an early online publication in Stem Cells Express.

10 Aug 2005

First evidence that complex genetic interactions account for autism risk

Using a novel analysis of the interactions among related genes, Duke University Medical Center researchers have uncovered some of the first evidence that complex genetic interactions account for autism risk. The Duke team found that the brain mechanism that normally stops or slows nerve impulses contributes to the disease.

3 Aug 2005

Customized gene chip offers clues to prognosis in cases of neuroblastoma

Rather than covering the entire genome, the microarray focuses on suspect regions of chromosomes for signs of deleted genetic material known to play a role in the cancer.

2 Aug 2005

Customized gene chip will offer clues to prognosis in cases of neuroblastoma

Genetics researchers have developed a customized gene chip to rapidly scan tumor samples for specific DNA changes that offer clues to prognosis in cases of neuroblastoma, a common form of children's cancer.

2 Aug 2005

Exposure to second-hand smoke during pregnancy can be just as detrimental to a developing fetus as primary exposure through maternal smoking

In a study published in the online journal BMC Pediatrics, Stephen G. Grant, Ph.D., associate professor of environmental and occupational health, reports that both active maternal smoking and secondary maternal exposure result in similarly increased rates of genetic mutation that are basically indistinguishable.

26 Jul 2005

Multi-species genome comparison sheds new light on evolutionary processes

An international team that includes researchers from the National Human Genome Research Institute (NHGRI) has discovered that mammalian chromosomes have evolved by breaking at specific sites rather than randomly as long thought - and that many of the breakage hotspots are also involved in human cancer.

25 Jul 2005

Scientists have identified the first genetic mutations that cause the aorta to widen, tear and rupture

Finding biological markers that flag aneurysm, a bulging of the aorta that leads to dissection, a lengthwise separation of tissues in the artery wall, is critically important for early diagnosis.

25 Jul 2005

Chromosome X News and Research

Further Reading

Gene mutation may increase the risk of prostate cancer up to three times in African-American

Suppression of FOXO1a gene might kill resistant alveolar rhabdomyosarcoma (ARMS) tumors

Acute-leukemia sign may signal need for different therapy

Nitric oxide could one day help women in their 30s and 40s remain fertile longer

Significant advance in the study of small ribonucleic acids

Overall genome landscape between chimps and humans can be attributed to large segmental duplications

Significant advance in the study of small ribonucleic acids

Toluidine blue dye reveals oral cancers

Human Y chromosome stays intact while chimp Y loses genes

Compound called GRN163L blocks lung cancer

Discovery of a potential oncogene in ovarian cancer

First proof of how the rare disorder Fanconi anemia causes chromosomal instability

Researchers have discovered a gene linked to age-related maculopathy

Placental tissue could feasibly provide an abundant source of cells with the same potential to treat diseases as embryonic stem cells

First evidence that complex genetic interactions account for autism risk

Customized gene chip offers clues to prognosis in cases of neuroblastoma

Customized gene chip will offer clues to prognosis in cases of neuroblastoma

Exposure to second-hand smoke during pregnancy can be just as detrimental to a developing fetus as primary exposure through maternal smoking

Multi-species genome comparison sheds new light on evolutionary processes

Scientists have identified the first genetic mutations that cause the aorta to widen, tear and rupture

Achieving and maintaining ISO/IEC 27001 and BS 10012 certifications

Expanding research and clinical options for children with cancer

Examining how pain could play a direct protective role in the gut

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