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.

EMA accepts Pfizer's regulatory submissions of two investigational cancer drugs for review

Pfizer Inc. announced today that the European Medicines Agency (EMA) has accepted Pfizer's regulatory submissions for review of two investigational compounds - crizotinib, an oral first-in-class anaplastic lymphoma kinase (ALK) inhibitor, for the treatment of patients with previously treated ALK-positive advanced non-small cell lung cancer (NSCLC); and bosutinib for the treatment of adult patients with newly diagnosed Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) in the chronic phase.

18 Aug 2011

G-CSF therapy does not induce chromosomal instability in healthy stem cell donors

According to a study published in Blood, the Journal of the American Society of Hematology (ASH), researchers have reported that administration of granulocyte colony-stimulating factor (G-CSF), a drug that releases stem cells from the bone marrow into the blood, is unlikely to put healthy stem cell donors at risk for later development of abnormalities involving loss or gains of chromosomes that have been linked to hematologic disorders such as myelodysplastic syndromes (MDS) and acute myeloid leukemia.

12 Aug 2011

Blood test early in pregnancy to detect baby’s gender

While carrying the child, a mother's blood has cell-free fetal DNA floating around in it, and it's possible to use this to test for the baby's sex. In a meta-analysis that covered more, the test was found to be 95% efficient in guessing the sex of the fetus — and it works from as early as seven weeks. As the fetus and the placenta develop, the amount of DNA present in the mother increases, boosting the accuracy of the test, which hits its peak at 20 weeks.

12 Aug 2011

Noninvasive prenatal DNA test can detect fetus at risk for sex-linked disorders

As a noninvasive method of determining the sex of a fetus, tests using cell-free fetal DNA obtained from the mother's blood after 7 weeks gestation performed well, while urine-based tests appear to be unreliable, according to a review and analysis of previous studies, reported in the August 10 issue of JAMA.

10 Aug 2011

Researchers discover gene variant linked to meningiomas

The causes of brain tumours have been hard to discern in most cases. But Umeå researchers have previously identified an inherited predisposition for brain tumours, and now, in an international collaboration, they have also discovered a genetic variation that increases the risk of a certain type of brain tumour, called meningiomas.

8 Aug 2011

Scientist urges federal officials to decide on genetically engineered salmon for consumption

A Purdue University scientist is urging federal officials to decide whether genetically engineered salmon would be allowed for U.S. consumption and arguing that not doing so may set back scientific efforts to increase food production.

6 Aug 2011

Higher levels of B cells make women more prone to autoimmune diseases

Researchers at National Jewish Health have discovered a type of cell that may contribute to autoimmune disease and suggests why diseases such as lupus, multiple sclerosis and rheumatoid arthritis strike women more frequently than men. The cells, a subset of immune-system B cells, make autoantibodies, which bind to and attack the body's own tissue.

5 Aug 2011

British scientists find seven new gene variants linked to prostate cancer

Cancer Research UK-funded scientists have taken a further step to identifying men at a greater risk of prostate cancer with the discovery of seven new variants in the human genome that increase the chances of developing the disease. The research is published in Nature Genetics.

3 Aug 2011

ARIAD reports $47.8 million net loss for second quarter 2011

ARIAD Pharmaceuticals, Inc. today reported financial results for the second quarter and six months ended June 30, 2010 and provided an update on corporate developments.

2 Aug 2011

Researchers identify gene linked to Lesch-Nyhan disease

In humans, inherited mutations in a gene called HPRT1 lead to very specific self-destructive behavior. Boys with Lesch-Nyhan disease experience uncontrollable urges to bite their fingers, slam their arms into doorways and otherwise harm themselves.

28 Jul 2011

Insect virus holds key to safer stem cell therapy: Singapore scientists

The future of regenerative medicine lies in harnessing the potential of the human body to renew and repair itself. Now, scientists at the Institute of Bioengineering and Nanotechnology (IBN), the world's first bioengineering and nanotechnology research institute, have developed a new genetic engineering technique that promises safer stem cell therapy for cancer patients. Using an insect virus, the team of researchers successfully inserted a therapeutic gene into a safe site in the DNA of human embryonic stem cells without compromising the functionality of the engineered cells.

28 Jul 2011

Carcinogenesis is just another form of speciation, proposes new theory

Cancer patients may view their tumors as parasites taking over their bodies, but this is more than a metaphor for Peter Duesberg, a molecular and cell biology professor at the University of California, Berkeley.

27 Jul 2011

Scientists identify possible genetic variations linked to eating disorders

A substantial number of people with eating disorders, such as anorexia nervosa have a chronic course. They are severely underweight and have a high likelihood of dying from malnutrition. No treatment has been found that helps people who are chronically ill. Now, a new study sheds light on the reason that some people have poor outcome.

27 Jul 2011

Two genetic variations can identify children at higher risk of radiation-induced second cancers

A genome-wide association study published in the August issue of Nature Medicine has found two tiny genetic variations that can predict which patients with Hodgkin's lymphoma are most likely to develop radiation-induced second cancers years after treatment.

25 Jul 2011

First high-resolution genetic maps for African American populations

UCLA life scientists and colleagues have produced one of the first high-resolution genetic maps for African American populations. A genetic map reveals the precise locations across the genome where DNA from a person's father and mother have been stitched together through a biological process called "recombination." This process results in new genetic combinations that are then passed on to the person's children.

25 Jul 2011

Health Canada approves SPRYCEL as first-line treatment for life-threatening blood cancer

Canadians newly diagnosed with a life-threatening blood cancer, chronic myeloid leukemia (CML) in chronic phase, now have a new treatment option available to them. Health Canada has granted a notice of compliance with conditions for SPRYCEL (dasatinib) as first-line treatment in patients with chronic phase CML.

22 Jul 2011

UCSF, Kaiser Permanente achieve first major milestone in genomics project

One of the nation's largest and most diverse genomics projects has reached its first major milestone in just 15 months. Scientists have genotyped the DNA and analyzed the length of chromosome tips in more than 100,000 Kaiser Permanente members who agreed to be part of the research.

22 Jul 2011

Researchers develop mouse model of rare human birth defect

A team of researchers from the University of Utah and Brigham Young University has developed a mouse model of focal dermal hypoplasia, a rare human birth defect that causes serious skin abnormalities and other medical problems. This animal model not only provides insight into studying the cause of focal dermal hypoplasia (FDH), but also offers a novel way to study a signaling pathway that is crucial for embryonic development.

21 Jul 2011

Nuclear Factor I/B appears to drive progression of small cell lung cancer

A major challenge for cancer biologists is figuring out which among the hundreds of genetic mutations found in a cancer cell are most important for driving the cancer's spread.

20 Jul 2011

Short telomeres may increase risk of emphysema

Telomeres, the body's own cellular clocks, may be a crucial factor underlying the development of emphysema, according to research from Johns Hopkins University.

15 Jul 2011