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.

UK researchers discover new tactic used by cancer cells to cheat death

Cancer Research UK scientists have uncovered a new strategy that could be used by cancer cells to side step the body's normal safety checks and become immortal a key step for a cancer cell according to a study published in Nature today (Thursday).

10 Sep 2010

Major contributing factor to maternal age-associated increase in aneuploidy identified

University of Pennsylvania biologists studying human reproduction have identified what is likely the major contributing factor to the maternal age-associated increase in aneuploidy, the term for an abnormal number of chromosomes during reproductive cell division.

9 Sep 2010

Researchers find minocycline antibiotics effective for fragile X syndrome

One of the antibiotics most commonly prescribed to treat adolescent acne can increase attention spans and communication and decrease anxiety in patients with fragile X syndrome, the most common inherited cause of mental impairment, according to a new survey study that is the first published on parents' reports of their children's responses to treatment with the medication.

9 Sep 2010

Researchers unveil protection mechanism of telomeres from DNA repair

In the latest issue of the journal Nature, Miguel Godinho Ferreira, Principal Investigator at the Instituto Gulbenkian de Ciência (IGC) in Portugal, lead a team of researchers to shed light on a paradox that has puzzled biologists since the discovery of telomeres, the protective tips of chromosomes: while broken chromosome ends generated by DNA damage (such as radiation or cigarette smoke) are quickly joined together, telomeres are never tied to each other, thus allowing for the correct segregation of the genetic material into all cells in our body.

9 Sep 2010

New insight into abnormalities in cancer cells

A basic requirement for growth and life of a multicellular organism is the ability of its cells to divide. Chromosomes in the cells duplicate and are then distributed among the daughter cells. This distribution is organized by a protein complex made up of several hundred different proteins, called the centrosome. In cancer cells, the centrosome often assumes an unnatural shape or is present in uncontrolled numbers. The reasons for this were previously largely unknown.

4 Sep 2010

Research on iPS cells can imply potential cell therapy for X-linked disorders

Female induced pluripotent stem (iPS) cells, reprogrammed from human skin cells into cells that have the embryonic-like potential to become any cell in the body, retain an inactive X chromosome, stem cell researchers at UCLA have found.

4 Sep 2010

Researchers develop new animal model for studying hemophilia A

Researchers at Yale School of Medicine have developed a new animal model for studying hemophilia A, with the goal of eventually treating people with the disorder.

3 Sep 2010

First direct evidence that X-linked TLR7 gene promotes lupus in humans

Lupus Research Institute-funded researcher Betty Tsao, PhD, at the University of California Los Angeles has discovered that humans-males in particular-with a variant form of the immune receptor gene "Toll Like Receptor 7 (TLR7)" are at increased risk of developing the autoimmune disease systemic lupus erythematosus (lupus). This breakthrough finding offers renewed hope for developing more targeted treatments.

3 Sep 2010

Simple protocol for determining Gross Chromosomal Rearrangement mutation rates

A cell devotes a significant amount of effort to maintaining the stability of its genome, preventing the sorts of chromosomal rearrangements characteristic of many cancers. Assays that measure the rate of gross chromosomal rearrangements (GCRs) are needed in order to understand the individual genes and the different pathways that suppress genomic instability.

3 Sep 2010

Genetic variations in Y chromosome affect men's risk of coronary heart disease: Scientists

Scientists in the UK have shown that genetic variations in the Y chromosome affect a male's risk of coronary heart disease. It is well known that males have a higher incidence of coronary heart disease than females due, in part, to the Y chromosome they inherit from their fathers. To investigate the role of the Y chromosome further, a team from the University of Leicester carried out research to determine whether genetic variations in the Y-chromosome affect risk for males.

30 Aug 2010

Study finds common risk factors linked with painkiller addiction

A new Geisinger study begins to unlock the puzzle of painkiller (opioid) addiction - why some people are more likely to become addicted than others. Geisinger investigators have found that patients with four common risk factors have a significantly higher risk of addiction. In addition, a history of severe drug dependence and drug abuse compounds the risk.

30 Aug 2010

Battery of tests for quick assessment of cognitive abilities in Down syndrome patients

Neuroscientists in the Down Syndrome Research Group at the University of Arizona have created a battery of tests that quickly aid in the assessment of the cognitive abilities of persons with Down syndrome.

27 Aug 2010

Fox Chase Cancer Center to host Philadelphia Chromosome Symposium

In celebration of a seminal discovery in cancer biology, Fox Chase Cancer Center will host the Philadelphia Chromosome Symposium: Past, Present and Future, on September 28, 2010, from 8 a.m. to 7 p.m. at The Chemical Heritage Foundation, 315 Chestnut Street, Philadelphia. The event marks the 50th anniversary of the discovery of the first genetic abnormality associated with cancer, and the first to lead to a targeted therapy for cancer.

25 Aug 2010

Researchers identify molecular signals that impact male fertility: Research

Male infertility is a common medical problem, affecting millions of men in the United States annually. Its causes include an inability to make productive sperm. Now, using yeast as a model organism, researchers at the University of Pennsylvania School of Medicine are beginning to identify the molecular signals that could in part underlie that problem.

25 Aug 2010

Research finds variation in sex chromosome may cause lupus in men

Genes reside along long chains of DNA called chromosomes. UCLA researchers have found that a variation in a gene on the sex chromosome X may enhance an immune response that leads to lupus in men.

24 Aug 2010

Researchers discover unusual property of meiosis may lead to Down syndrome

In a study of egg cells using time-lapse microscopy, researchers at the University of California, San Diego School of Medicine and the Ludwig Institute for Cancer Research have discovered an unusual property of meiosis - cell division that produces reproductive cells in sexually reproducing organisms.

23 Aug 2010

Researchers find new way to study oncogene's role in DNA repair

A key step in understanding the origins of familial breast cancer has been made by two teams of scientists at the University of California, Davis. The researchers have purified, for the first time, the protein produced by the breast cancer susceptibility gene BRCA2 and used it to study the oncogene's role in DNA repair.

23 Aug 2010

US oncology announces its contributions in development of 42 novel cancer therapies

US Oncology, Inc., the nation's leading integrated oncology company, announced today that in less than two decades it has played a role in the development of 42 novel cancer therapies approved by the US Food and Drug Administration.

21 Aug 2010

Study finds genetic change in chromosome 4 causes FSHD

The Muscular Dystrophy Association today heralds a landmark muscular dystrophy advance by an international study team of scientists and physicians from the Netherlands, United States, France and Spain. Led by MDA-grantee Silvère van der Maarel, Ph.D., at Leiden University Medical Center in the Netherlands, the collaborative study of more than 2,300 people found that two distinct genetic changes on chromosome 4 must be present to cause facioscapulohumeral muscular dystrophy (FSHD).

21 Aug 2010

Tasigna receives approval for chronic myeloid leukemia in Canada

Tasigna (nilotinib) capsules have been approved with conditions in Canada as a new therapy for patients with CML, in the chronic phase (first phase) of the disease. Patients must be resistant to or intolerant of at least one prior therapy, including (Pr)Gleevec (imatinib mesylate), an established standard of care.

20 Aug 2010