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 that regulates normal embryonic development is found at high levels in virtually all forms of breast cancer

A gene that appears to help regulate normal embryonic development is found at high levels in virtually all forms of breast cancer, according to a new study led by Laszlo Radvanyi, Ph.D., associate professor of breast and melanoma medical oncology at The University of Texas M. D. Anderson Cancer Center.

25 Jul 2005

New insight into age-related macular degeneration

Age-related macular degeneration is the leading cause of blindness in older adults, yet researchers are still in the dark about many of the factors that cause this incurable disease.

25 Jul 2005

Multiple rare mutations within a single gene may increase risk for autism

While debate still rages over the 'cause' of autism, mounting evidence suggests that genetic factors play a major role in the disease.

25 Jul 2005

Hidden secrets on the nature and timing of genome evolution in mammals revealed

Breakages in chromosomes in mammalian evolution have occurred at preferred rather than random sites as long thought, and many of the sites are involved in human cancers, an international team of 25 scientists has discovered.

21 Jul 2005

Two regions of the human genome that appear to explain variation in IQ

It may be that IQ tests are not the only way to measure human intelligence. Scientists at The Queensland Institute of Medical Science (QIMR) have identified two regions of the human genome that appear to explain variation in IQ. Their work was published this week in the American Journal of Human Genetics and has drawn world-wide interest.

19 Jul 2005

Extraordinary number of genes are required for prenatal mammalian development

A team of scientists led by Cornell University's Dr. John Schimenti reports today that an extraordinary number of genes are required for prenatal mammalian development. The researchers estimate that up to 19% of all genes are vital for embryogenesis in mice.

17 Jul 2005

Chromos Molecular Systems issued four key patents

Chromos Molecular Systems has announced that it has further expanded the patent portfolio surrounding both its ACE System and REM Technology with the issuance of four key additional patents.

15 Jul 2005

Researchers find genetically controlled brain mechanism responsible for social behavior in humans

Researchers at the National Institute of Mental Health (NIMH) have discovered a genetically controlled brain mechanism responsible for social behavior in humans--one of the most important but least understood aspects of human nature.

13 Jul 2005

Researchers have pinpointed specific gene and protein over-production in metastatic melanoma

Gene amplification is a process that often happens in cancer cells when the normal DNA replication process is altered, causing many copies of the gene to be produced instead of a single copy of a region of a chromosome.

12 Jul 2005

Researchers discover genetically controlled brain mechanism responsible for social behavior in humans

Researchers at the National Institute of Mental Health (NIMH) have discovered a genetically controlled brain mechanism responsible for social behavior in humans - one of the most important but least understood aspects of human nature. The findings are reported in Nature Neuroscience.

11 Jul 2005

Changes to prenatal genetic testing could mean more babies born with abnornalities

A study in the UK suggests that a proposed change to the type of prenatal genetic testing offered to couples in the UK, could possibly result in certain chromosome abnormalities being missed.

4 Jul 2005

Birth abnormality rates could increase if proposed changes to prenatal testing go ahead

A proposed change to the type of prenatal genetic testing offered to couples in the UK could result in certain chromosome abnormalities being missed, suggests a study published online today (Thursday June 30, 2005) by The Lancet.

1 Jul 2005

New initiative to provide $600k to fund new research into Down Syndrome

Today the University of Colorado and The Anna and John J. Sie Foundation of Denver announced The Sie Family Down Syndrome Break-Through Research Initiative. The initiative will provide $600,000 in grant funds to stimulate new scientific research on Down syndrome with the aim of enhancing cognitive ability. These are the first such grants provided to CU for a specific chromosomal condition and the first nationwide specifically for Down syndrome.

1 Jul 2005

Exercise helps find genetic regions linked to prediabetes

People's bodies respond to exercise in different ways, and their genetic makeup is partly responsible.

28 Jun 2005

New clues about the location of genes potentially involved in the most common type of lung cancer

Using technology that makes it possible to zoom in on smaller sections of cell chromosomes than ever before, researchers at Dana-Farber Cancer Institute have identified nearly 100 chromosome regions where genes are either over-copied or missing in non-small cell lung cancer.

27 Jun 2005

Technique called phylogenetic footprinting reveals new gene regulation system

By comparing 140 sequenced bacterial genomes, researchers have uncovered a system for regulating genes essential to bacterial replication - and they did it solely by computer keystrokes and mouse clicks.

27 Jun 2005

Foxp2 gene plays an essential role in the development of social communication

The association between Foxp2 and language was first identified in a family in which half the members had severe speech and grammar impairments. Studies showed that all the affected family members had a mutation in the Foxp2 gene.

21 Jun 2005

Early embryos with abnormal chromosomes are capable of returning to normal when grown in culture in the laboratory

While such embryos are not capable of developing into normal foetuses if implanted in a woman's womb, the discovery has important implications for stem cell production, especially in countries where the creation of embryos for stem cell research is discouraged or even banned.

20 Jun 2005

Scientists have tracked down the biological trigger that gives rise to Van Buchem disease

...a hereditary, disfiguring bone disorder that can cause blindness and deafness. The findings provide insight into long-range gene regulation and could lead to new treatments for osteoporosis and other crippling bone disorders.

16 Jun 2005

Research challenges the evolutionary paradigm that continuous alterations occur during the course of genome evolution

Researchers report today that regions of the human genome have been hotspots for acquiring duplicated DNA sequences - but only at specific time-points during evolution.

16 Jun 2005

Chromosome X News and Research

Further Reading

Gene that regulates normal embryonic development is found at high levels in virtually all forms of breast cancer

New insight into age-related macular degeneration

Multiple rare mutations within a single gene may increase risk for autism

Hidden secrets on the nature and timing of genome evolution in mammals revealed

Two regions of the human genome that appear to explain variation in IQ

Extraordinary number of genes are required for prenatal mammalian development

Chromos Molecular Systems issued four key patents

Researchers find genetically controlled brain mechanism responsible for social behavior in humans

Researchers have pinpointed specific gene and protein over-production in metastatic melanoma

Researchers discover genetically controlled brain mechanism responsible for social behavior in humans

Changes to prenatal genetic testing could mean more babies born with abnornalities

Birth abnormality rates could increase if proposed changes to prenatal testing go ahead

New initiative to provide $600k to fund new research into Down Syndrome

Exercise helps find genetic regions linked to prediabetes

New clues about the location of genes potentially involved in the most common type of lung cancer

Technique called phylogenetic footprinting reveals new gene regulation system

Foxp2 gene plays an essential role in the development of social communication

Early embryos with abnormal chromosomes are capable of returning to normal when grown in culture in the laboratory

Scientists have tracked down the biological trigger that gives rise to Van Buchem disease

Research challenges the evolutionary paradigm that continuous alterations occur during the course of genome evolution

Expanding research and clinical options for children with cancer

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

From Puberty to Menopause: Clue’s CEO, Audrey Tsang on the Power of Femtech

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