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.

Bosutinib safe, effective for chronic myelogenous leukemia

A new drug for chronic myelogenous leukemia works for patients who have developed resistance to frontline therapy and causes fewer side effects than other medications in its class, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reports at the 49th annual meeting of the American Society of Hematology.

12 Dec 2007

Data confirm Dasatinib's effectiveness in resistant chronic myelogenous leukemia

Updated clinical trial results show that the drug dasatinib (Sprycel) continues to be highly effective in patients with chronic myelogenous leukemia who were unable to tolerate Gleevec or who developed resistance to it, reports a team led by researchers at Dana-Farber Cancer Institute.

12 Dec 2007

Genetic evidence that human evolution is speeding up

Researchers discovered genetic evidence that human evolution is speeding up – and has not halted or proceeded at a constant rate, as had been thought – indicating that humans on different continents are becoming increasingly different.

10 Dec 2007

Nicotine has significant effects on brain GABA

There is a clear link between GABA - a chemical substance of the central nervous system that inhibits neurons in the brain - and nicotine dependence, according to a study presented at the American College of Neuropsychopharmacology (ACNP) annual meeting.

10 Dec 2007

New understanding of chronic myeloid leukemia

Oregon Health & Science University Cancer Institute researchers have opened a new window into the roots of chronic myeloid leukemia (CML).

10 Dec 2007

Study shows how mutations in the BRCA1 gene lead to breast cancer

An international team of researchers led by Columbia University Medical Center's Herbert Irving Comprehensive Cancer Center and Sweden's Lund University has, for the first time, revealed how mutations in the BRCA1 gene lead to breast cancer.

10 Dec 2007

More good Gleevec news

Gleevec, the targeted cancer pill that has saved more than 100,000 lives, now is saving more children with a dire leukemia, as well as preventing disease progression with long term use in adults with chronic myeloid leukemia.

10 Dec 2007

Nilotinib and Dasatinib show promise as therapy for chronic myelogenous leukemia

Two drugs approved for use as second line therapy for chronic myelogenous leukemia are showing promising results as frontline therapy for newly diagnosed patients in two clinical trials, research teams led by scientists at The University of Texas M. D. Anderson Cancer Center report at the 49th annual meeting of the American Society of Hematology.

10 Dec 2007

Re-engineered Gleevec reduces heart risks

Using a new bottom-up approach for rational drug design, researchers at Rice University and the University of Texas M. D. Anderson Cancer Center have reengineered the powerful anticancer drug imatinib - best known by its brand name Gleevec - to more specifically target one type of cancer while potentially curbing a rare life-threatening cardiotoxic side effect.

4 Dec 2007

First map of imprinted genes in human genome

Scientists at Duke University have created the first map of imprinted genes throughout the human genome, and they say a modern-day Rosetta stone – a form of artificial intelligence called machine learning – was the key to their success.

2 Dec 2007

Study of Mexican Americans shows that polymorphisms of the CYP2E1 gene enhance susceptibility to alcoholism

Mexican Americans make up 66 percent of the U.S. Hispanic population and, when compared to other ethnic groups, show high rates of heavy drinking and alcohol-related problems.

27 Nov 2007

There is a new twist on the question of how biological clocks work

In recent years, scientists have discovered that biological clocks help organize a dizzying array of biochemical processes in the body. Despite a number of hypotheses, exactly how the microscopic pacemakers in every cell in the body exert such a widespread influence has remained a mystery.

21 Nov 2007

Why are males in evolutionary overdrive even though they have essentially the same genes as females?

The observation that males evolve more quickly than females has been around since 19th century biologist Charles Darwin noted the majesty of a peacock's tail feather in comparison with the plainness of the peahen's.

15 Nov 2007

Human RecQ helicases, homologous recombination and genomic instability

Two independent papers in the December 1st issue of G&D detail how human RecQ helicases regulate homologous recombination and protect genome stability.

15 Nov 2007

Are there rearrangement hot spots in the human genome?

The debate over the validity of genomic rearrangement "hotspots" has its most recent addition in a new theory put forth by researchers at the University of California San Diego.

13 Nov 2007

Sex ratio skew explained

If you met a person who had 10 children, all of whom were girls, you would probably find this surprising.

6 Nov 2007

New view of lung cancer genome

An international team of scientists, supported in part by the National Human Genome Research Institute (NHGRI), one of the National Institutes of Health (NIH), have announced that its systematic effort to map the genomic changes underlying lung cancer has uncovered a critical gene alteration not previously linked to any form of cancer.

5 Nov 2007

Researchers identify gene behind rheumatoid arthritis

University of Manchester researchers have identified a genetic variant in a region on chromosome 6 that is associated with rheumatoid arthritis (RA), the most common inflammatory arthritis affecting 387,000 people in the UK.

From The University of Manchester 5 Nov 2007

Comprehensive view of the abnormal genetic landscape in lung cancer cells

An international team of scientists has announced the results of a systematic effort to map the genetic changes underlying lung cancer, the world's leading cause of cancer deaths.

5 Nov 2007

Manipulation of MOF enzyme may make tumors more sensitive to radiation therapy

To make tumors more sensitive to the killing power of radiation is a key aspiration for many radiation oncologists. Researchers at Washington University School of Medicine in St. Louis have uncovered new information that leads them closer to that goal.

5 Nov 2007