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.

Vaccine that boosts the immune response could improve the effect of conventional treatment for patients with chronic myeloid leukaemia

CML is caused by the breakage and swapping of chromosomes 9 and 22, which results in a shortened chromosome called the Philadelphia chromosome. Cells with the abnormal chromosome make a protein that encourages aberrant growth and division. Patients with CML can be treated with a drug called imatinib or interferon alfa.

20 Feb 2005

Separating chromosomes improves genetic test results

A new process that helps unmask genetic mutations by separating chromosomes so they can be studied individually may improve the diagnostic yield of some genetic tests, according to findings of a Colon Cancer Family Registry study published today in the Journal of the American Medical Association.

16 Feb 2005

Angiogenesis inhibitor molecules defend against the development and spread of cancer

Research led by investigators at Beth Israel Deaconess Medical Center (BIDMC) helps explain how a group of angiogenesis inhibitor molecules serve as an important defense mechanism against the development and spread of cancer, offering key insights into why cancerous tumors grow at different rates among different individuals.

15 Feb 2005

Exposure of expectant mothers to urban air pollution may alter the structure of babies' chromosomes while in the womb

A new study of 60 newborns in New York City reveals that exposure of expectant mothers to combustion-related urban air pollution may alter the structure of babies' chromosomes while in the womb.

15 Feb 2005

New primate-specific gene family that spans about 10% of human chromosome 2

A team of scientists led by Peer Bork, Ph.D., Senior Bioinformatics Scientist at the European Molecular Biology Laboratory, report today in the journal Genome Research that they have identified a new primate-specific gene family that spans about 10% of human chromosome 2.

13 Feb 2005

Experimental drug Revlimid showing promise as treatment for myelodysplastic syndrome (MDS)

Alan List, M.D., leader of the Hematologic Malignancies Program at the H. Lee Moffitt Cancer Center & Research Institute, recently conducted a phase I/II trial of the experimental drug Revlimid showing promise as an innovative way to treat patients with myelodysplastic syndrome (MDS), a form of pre-leukemia.

10 Feb 2005

Short girls with underlying disease are not being diagnosed

Twice as many boys as girls are referred to medical specialists for evaluation of short stature or poor growth, according to a new study.

7 Feb 2005

Gene used in brain development can cause childhood brain cancers

A gene that's normally silenced after contributing to brain development was found to be expressed in cells from medulloblastoma, the most common form of pediatric brain malignancy in children, scientists report in an article published in the February 1 issue of the journal Cancer Research.

3 Feb 2005

Do genes play a role in determining whether a man is gay or heterosexual?

In the first-ever study combing the entire human genome for genetic determinants of male sexual orientation, a University of Illinois at Chicago researcher has identified several areas that appear to influence whether a man is heterosexual or gay.

31 Jan 2005

Genetic defect leads to electrical instability and mechanical pump failure

In genetic mapping of a large family with several members affected by a type of heart failure called dilated cardiomyopathy (DCM), the Mayo Clinic team found a defect in a gene on chromosome 3 called SCN5A.

26 Jan 2005

High blood pressure risk in African-Americans linked to genetics

National health records have shown that African-Americans are more prone to high blood pressure than Caucasians, but pinning down the roots of that difference has proven elusive. Now, researchers at the Stanford University School of Medicine have narrowed down the search for genes that contribute to this difference in disease risk.

24 Jan 2005

Missing sequence of the human Y chromosome may contain genes controlling stature and tumor development

Scientists have reported in the journal Genome Research that they have successfully cloned and characterized a previously intractable DNA sequence: a 554-kilobase-pair genomic segment near the centromere of the human Y chromosome. This sequence contains eight putatively active genes that could be implicated in sex-associated height differences and gonadal tumor development.

16 Jan 2005

Using models to understand malaria

Malaria is one of the world's major killers. More than 500 million people live in epidemic regions and some 2 million - mostly children - die each year. And each year, drug resistance increases in the malarial parasite, Plasmodium falciparum, and the search for new treatments becomes more desperate.

12 Jan 2005

Corticosteroids can be beneficial in the treatment of Duchenne muscular dystrophy

Corticosteroids can be beneficial in the treatment of Duchenne muscular dystrophy and can be offered as a treatment option, according to the American Academy of Neurology and the Child Neurology Society in a new practice guideline published in the January 11 issue of Neurology, the scientific journal of the American Academy of Neurology.

10 Jan 2005

Novel Structure Proteins (NSP) could help predict the possibility of tumor growth in a patient

A new family of genes called Novel Structure Proteins (NSP) discovered by researchers in the Sbarro Institute for Cancer Research and Molecular Medicine in Temple University’s College of Science and Technology could have the potential for predicting the possibility of tumor growth in a patient.

9 Jan 2005

New genetic clues provide better understanding of epilepsy

Two specific areas in chromosome 7 and chromosome 16 have been associated with photosensitivity, an epilepsy-related trait, by a team of European scientists in the January issue of Human Molecular Genetics.

5 Jan 2005

Direct modulation of progesterone signaling appears to influence ovarian cancer risk

A woman's risk of ovarian cancer rises significantly if she carries either of two previously unexamined variations in the gene that codes for the progesterone receptor, according to a team of researchers led by scientists from the Keck School of Medicine of the University of Southern California.

5 Jan 2005

Genomics tools provide clues to what causes 400 million cases of gastrointestinal disease each year

In a study that could benefit medical and food-safety research, scientists have used comparative genomics tools to find clues about why some strains of the bacterium Campylobacter – which each year cause more than 400 million cases of gastrointestinal disease – are more virulent than others.

4 Jan 2005

Needling chromosomes yields insights into cell division

By impaling individual chromosomes with glass needles one thousandth the diameter of a human hair, a Duke University graduate student has tested their "stickiness" to one another during cell division. Her uncanny surgical skills have added a piece to the large and intricate puzzle of how one cell divides into two -- a process fundamental to all organisms.

23 Dec 2004

Mutant gene that starves the brain of serotonin 10 times more prevalent in depressed patients

A mutant gene that starves the brain of serotonin, a mood-regulating chemical messenger, has been discovered and found to be 10 times more prevalent in depressed patients than in control subjects, report researchers funded by the National Institutes of Health’s National Institute of Mental Health (NIMH) and National Heart Lung and Blood Institute (NHLBI).

21 Dec 2004