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.

Culprit found in rare type of baldness

Scientists in Beijing say they have discovered a genetic cause for a certain type of premature baldness and they suggest their discovery offers hope in future that those who inherit this rare type of baldness will eventually be able to keep their hair.

5 Jan 2009

New understanding of genetic signature associated with Alzheimer's disease

Scientists have new information about the complex genetic signature associated with Alzheimer's disease, the leading cause of cognitive decline and dementia in the elderly.

1 Jan 2009

In lung cancer, silencing one crucial gene disrupts normal functioning of genome

While examining patterns of DNA modification in lung cancer, a team of international researchers has discovered what they say is a surprising new mechanism.

1 Jan 2009

Researchers identify common gene variant linked to high blood pressure

Researchers at the University of Maryland School of Medicine have identified a common gene variant that appears to influence people's risk of developing high blood pressure, according to the results of a study being published online Dec. 29, 2008 in the Proceedings of the National Academy of Sciences (PNAS).

30 Dec 2008

Ancient African exodus mostly involved men

Modern humans left Africa over 60,000 years ago in a migration that many believe was responsible for nearly all of the human population that exist outside Africa today.

21 Dec 2008

Borderline personality disorder more common than schizophrenia

According to the National Institute of Mental Health, borderline personality disorder (BPD) is more common than schizophrenia or bipolar disorder and is estimated to affect 2 percent of the population.

16 Dec 2008

Fatherhood gene determines if it's a boy or a girl

According to recent research whether men are likely to father a boy or a girl is determined by a "fatherhood gene".

15 Dec 2008

New research moves us one step closer to personalised breast cancer treatment

Cancer Research UK scientists have found that a test, already used in breast cancer diagnosis, can also predict who will and who won't benefit from commonly used chemotherapy drugs.

15 Dec 2008

New understanding of mechanism that regulates DNA methylation

Researchers in a University of Oregon lab have shed more light on the mechanism that regulates DNA methylation, a fundamental biological process in which a methyl group is attached to DNA, the genetic material in cells of living organisms.

14 Dec 2008

Promising clinical trial for Progeria "premature aging" disease

One of the fastest translations of a basic research discovery into a promising clinical trial for an "untreatable" and fatal disorder will be discussed publicly for the first time by the key players in this remarkable research story, on Sunday, Dec. 14, at the American Society for Cell Biology (ASCB)'s annual meeting in San Francisco.

14 Dec 2008

Good news for young male cancer patients

"Young men undergoing treatment for cancer often want to know how the disease and its treatment affect their chances of fathering healthy children. Our large-scale study shows that there is a slightly higher risk of deformities, but the actual risk of having a child with deformities is nevertheless extremely low. I think this is good news!"

14 Dec 2008

New cause of atrial fibrillation found

A new study shows that atrial fibrillation--the most common form of sustained heart arrhythmia--can be caused in an unexpected way.

12 Dec 2008

Enzyme that mutates antibodies also targets cancer-causing gene

The human immune system is in a perpetual state of self-experimentation. It expertly mutates and shuffles the DNA of its own cells to evolve new defenses against the vast array of microbes that try to invade our bodies.

12 Dec 2008

Researchers capture never before seen undulations of "dancing chromosomes"

The rhythm of life may beat far deeper than anyone previously thought. And it may gyrate and pulse in a way that rivals the sensuous choreography of "Dirty Dancing."

12 Dec 2008

Men inherit tendency to have more sons or more daughters from their parents

A Newcastle University study involving thousands of families is helping prospective parents work out whether they are likely to have sons or daughters.

12 Dec 2008

Enzyme that mutates antibodies also targets a cancer-causing oncogene

Rockefeller University scientists have discovered that the same enzyme that enables the immune system's defensive creativity is also responsible for a particular genetic malfunction - a translocation of one piece of DNA to the wrong chromosome - that causes Burkitt's lymphoma.

12 Dec 2008