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.

DNA sequencing of maternal blood plasma can accurately detect trisomy 21

In a study published online today in the American Journal of Obstetrics & Gynecology, researchers from the Sequenom Center for Molecular Medicine confirmed that DNA sequencing of maternal blood plasma could accurately detect trisomy 21.

10 Feb 2011

Scientists develop novel approach to detect long-distance chromosomal interactions for CAD

The discovery that a "gene desert" on chromosome 9 was a hotspot for coronary artery disease (CAD) risk was among the highlights of findings produced recently by genome-wide association studies, which compare the genomes of many people for genetic variations and have been broadly used in the past few years to study hundreds of diseases and complex traits. Gene deserts are large genomic segments devoid of genes.

10 Feb 2011

Scientists reprogram marrow cells from patient with chronic myeloid leukemia

By coaxing healthy and diseased human bone marrow to become embryonic-like stem cells, a team of Wisconsin scientists has laid the groundwork for observing the onset of the blood cancer leukemia in the laboratory dish.

4 Feb 2011

International scientist team identifies gene mutation strongly linked to schizophrenia

In a major advance for schizophrenia research, an international team of scientists, led by Jonathan Sebat, PhD, assistant professor of psychiatry and cellular and molecular medicine at the University of California, San Diego School of Medicine, has identified a gene mutation strongly linked to the brain disorder - and a signaling pathway that may be treatable with existing compounds.

3 Feb 2011

Research provides new clues for compulsive behavior, cognitive defects linked with LND

Research from the University of California, San Diego School of Medicine provides new clues for the compulsive behavior and cognitive defects associated with a rare childhood neurological disease called Lesch-Nyhan Disease.

29 Jan 2011

University of California study may shed light on human ability to adapt hypoxia

In an important study that may shed light on human ability to adapt to hypoxia, or inadequate levels of oxygen, researchers at the University of California, San Diego School of Medicine have proven that the genome of flies exposed to long-term hypoxia are changed to permanently affect gene expression.

24 Jan 2011

Researchers identify PBRM1 gene mutation in one in three patients with common form of renal cancer

In a collaborative project involving scientists from three continents, researchers have identified a gene that is mutated in one in three patients with the most common form of renal cancer.

20 Jan 2011

New Down syndrome non-invasive test for ‘mums-to-be’ on the horizon

According to experts a simple DNA test for Down syndrome could save nearly all pregnant women from invasive tests like amniocentesis. Usually 3% to 5% of pregnant women in the UK or some 30,000 women have to undergo invasive tests like amniocentesis that increases the risk of miscarriage to 1%. The new DNA blood test could bring this down to 0.1%, according to a study in the British Medical Journal.

12 Jan 2011

New mechanisms of resistance to chemotherapy among leukemia patients

The interplay between a major tumor-suppressing gene, a truncated chromosome and two sets of microRNAs provides a molecular basis for explaining the less aggressive form of chronic lymphocytic leukemia, an international team of researchers reports today in the Jan. 4 edition of the Journal of the American Medical Association.

10 Jan 2011

Single cellular crisis shatters chromosomes in cancer causation

Remarkable new research overthrows the conventional view that cancer always develops in a steady, stepwise progression. It shows that in some cancers, the genome can be shattered into hundreds of fragments in a single cellular catastrophe, wreaking mutation on a massive scale.

7 Jan 2011

Chromosome shattering seen in two to three percent of all cancers

Most of the time cancer seems to creep up gradually over time; cells become premalignant, then increasingly abnormal before they become cancerous. But sometimes cancers seem to pop up as if out of nowhere. Now, researchers reporting in the January 7th issue of the journal Cell, a Cell Press publication, have new evidence to explain how that can happen.

7 Jan 2011

Low levels of microbe-killing molecules improve survival rate of people with CGD

Investigators at the National Institutes of Health have observed that the survival rate of people with a rare immunodeficiency disease called chronic granulomatous disease is greatly improved when even very low levels of microbe-killing molecules are present.

30 Dec 2010

BIOMICs oversees SGIker DNA Bank to know genetic heritage of Basque lineage

The BIOMICs Group, based at the Lucio Lascaray building in the álava/Araba campus of the University of the Basque Country, is specially known for overseeing the SGIker DNA Bank, not only undertaking this task, but also feeding data into the gene research bank and making good use of it for their own lines of research.

28 Dec 2010

Study sheds light on how bacteria developed resistance to antibiotics

Studying how bacteria incorporate foreign DNA from invading viruses into their own regulatory processes, Thomas Wood, professor in the Artie McFerrin Department of Chemical Engineering at Texas A&M University, is uncovering the secrets of one of nature's most primitive immune systems.

27 Dec 2010

Catalogs of fruit fly and roundworm's functional genomic elements

Scientists today published catalogs of the fruit fly and roundworm's functional genomic elements: DNA sequences in the genome that carry the instructions and determine which genes are turned on and off at various times in different cells.

23 Dec 2010

Overexpression of Sox3 gene in mice causes XX male sex reversal

A team of researchers, led by Paul Thomas, University of Adelaide, Australia, has now determined that overexpression of the Sox3 gene in mice causes frequent XX male sex reversal.

23 Dec 2010

Sequenom CMM authorizes SensiGene T21 LDT clinical validation study

Sequenom, Inc. today announced that the company's wholly-owned reference laboratory, the Sequenom Center for Molecular Medicine (Sequenom CMM), has authorized commencement of a pivotal clinical validation study. This validation study is designed to evaluate the clinical performance of the SensiGene T21 Laboratory Developed Test (LDT) for the detection of an overabundance in maternal blood of chromosome 21, which is associated with fetal chromosome 21 aneuploidy.

23 Dec 2010

Male mice created without Y chromosome

University of Adelaide researchers are a step closer to unraveling the mysteries of human sexual development, following genetic studies that show male mice can be created without a Y chromosome - through the activation of an ancient brain gene.

23 Dec 2010

Gene changes during brain development can lead to male genitalia formation in female embryo

Australian scientists have discovered that changes to a gene involved in brain development can lead to testis formation and male genitalia in an otherwise female embryo.

22 Dec 2010

Top ten advances in cardiovascular, stroke research in 2010

Research on reducing risks, improving medical treatment and improving lifestyle behaviors to fight the battle against heart disease and stroke are among the key scientific findings that make up this year's top cardiovascular and stroke research recognized by the American Heart Association/American Stroke Association.

22 Dec 2010