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.

Research focuses on evolution of sex and gamete function

The propagation of every animal on the planet is the result of sexual activity between males and females of a given species. But how did things get this way? Why two sexes instead of one? Why are sperm necessary for reproduction and how did they evolve? These as-yet-unresolved issues fascinate Timothy Karr, a developmental geneticist and evolutionary biologist at Arizona State University's Biodesign Institute.

13 Aug 2012

FDA approved drug to treat Ph- acute lymphoblastic leukemia

The U.S. Food and Drug Administration today approved Marqibo (vincristine sulfate liposome injection) to treat adults with a rare type of leukemia called Philadelphia chromosome negative (Ph-) acute lymphoblastic leukemia (ALL). ALL is a rapidly progressing form of blood and bone marrow cancer that is more commonly diagnosed in children than adults.

10 Aug 2012

Researchers discover genetic cause of type VII mucopolysaccharidosis in Brazilian Terriers

The genetics research group led by Professor Hannes Lohi, based at the University of Helsinki and the Folkh-lsan Research Center, has, in collaboration with Adjunct Professor Kirsi Sainio's research group, discovered the cause of a life-threatening skeletal disorder affecting Brazilian Terriers. The disease is caused by a mutation in the GUSB gene.

7 Aug 2012

New research center to expedite study of gene transfer approach

In an alliance aimed at bringing a new, personalized immunotherapy approach to patients with a wide variety of cancers, the University of Pennsylvania and Novartis announced today an exclusive global research and licensing agreement to further study and commercialize novel cellular immunotherapies using chimeric antigen receptor (CAR) technologies.

6 Aug 2012

Associate director of Clinical Genetics receives Angelo DiGeorge Medal of Honor

Donna McDonald-McGinn, M.S., CGC, associate director of Clinical Genetics and program director of the "22q and You" Center at The Children's Hospital of Philadelphia, received the Angelo DiGeorge Medal of Honor on July 6 at the 8th Biennial International 22q11.2 DS Conference in Lake Buena Vista, Florida. Ms. McDonald-McGinn, who began her career at CHOP in 1985, is the second person to receive this highly esteemed honor.

6 Aug 2012

Novartis, Penn partner to study and commercialize novel cellular immunotherapies for cancer

6 Aug 2012

Similar molecular pathways involved in intellectual disability due to Fragile X and Down syndromes

Intellectual disability due to Fragile X and Down syndromes involves similar molecular pathways report researchers in The EMBO Journal. The two disorders share disturbances in the molecular events that regulate the way nerve cells develop dendritic spines, the small extensions found on the surface of nerve cells that are crucial for communication in the brain.

3 Aug 2012

Researchers identify how telomerase is recruited to chromosome ends

Stem cells are special. Nestled in muscle and skin, organ and bone, they bide their time over years or decades until called to replace damaged or lost tissue. One secret to their longevity is an enzyme called telomerase, which stills the relentless ticking of the molecular clock that limits the life span of other cells.

3 Aug 2012

Orc1 mutations may explain pathology in manifestations of Meier-Gorlin syndrome

Research published Aug. 1 by scientists at Cold Spring Harbor Laboratory (CSHL) links gene mutations found in some patients with Meier-Gorlin syndrome (MGS) with specific cellular dysfunctions that are thought to give rise to a particularly extreme version of dwarfism, small brain size, and other manifestations of abnormal growth which generally characterize that rare condition.

1 Aug 2012

Cepheid launches new Xpert BCR-ABL Monitor test

Cepheid today announced the release of an updated Xpert BCR-ABL Monitor test, now incorporating lot-specific standardization using the WHO (World Health Organization) BCR-ABL standards.

25 Jul 2012

Karyopharm commences two KPT-330 phase 1 studies in cancers

Karyopharm Therapeutics Inc., a leader in the new field of nuclear transport modulators, announced dosing of patients in the first-in-human clinical trials with KPT-330.

25 Jul 2012

Genetic underpinnings of Wiedemann-Steiner syndrome identified

Researchers have identified a genetic underpinning of Wiedemann-Steiner syndrome.

23 Jul 2012

Kids with T13 or 18 and their families lead a happy life

Children with trisomy 13 or 18, who are for the most part severely disabled and have a very short life expectancy, and their families lead a life that is happy and rewarding overall, contrary to the usually gloomy predictions made by the medical community at the time of diagnosis, according to a study of parents who are members of support groups published today in Pediatrics.

23 Jul 2012

Five rare mutations in single gene increase chances of boys developing ASD

Researchers at Emory University School of Medicine have identified five rare mutations in a single gene that appear to increase the chances that a boy will develop an autism spectrum disorder (ASD).

13 Jul 2012

DRCRF names 21 new Damon Runyon Fellows

The Damon Runyon Cancer Research Foundation, a non-profit organization focused on supporting innovative early career researchers, named 21 new Damon Runyon Fellows at its spring Fellowship Award Committee review.

11 Jul 2012

Osteoarthritis gene tic markers identified

Scientists have used data from the Arthritis Research UK Osteoarthritis Genetics study to identify five gene loci significantly associated with the development of the disease.

10 Jul 2012

Safe optimal concentration of propolis against radiation-induced damage

Researchers determined the amount of propolis offering maximum protection against ionised radiations without being toxic to blood cells.

7 Jul 2012

Bioengineers develop microfluidic platform to mechanically confine cancer cells

It's well known in conventional biology that during the process of mammalian cell division, or mitosis, a mother cell divides equally into two daughter cells. But when it comes to cancer, say UCLA researchers, mother cells may be far more prolific.

6 Jul 2012

Toxins and cell death: Interview with Professor Denise Montell

There are multiple kinds of cell death. Cells can undergo programmed cell death, which is a series of events that undergoes a predictable order at certain times during development.

6 Jul 2012

Study represents starting point for future clinical applications using propolis

A team of researchers from the University of Valencia, the Universitat Politècnica de València, the University Hospital La Fe and the Universitat Autònoma de Barcelona conducted in vitro studies of cytotoxicity (cellular affection) to assess the optimal concentration level of propolis in which this natural substance extracted from bee resin would offer the maximum protection against ionised radiation and not be toxic for blood cells.

6 Jul 2012