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.

Researchers identify genome-wide locus for serious gastrointestinal condition in infants

Researchers have identified a new genome-wide significant locus (the place a gene occupies on a chromosome) for infantile hypertrophic pyloric stenosis (IHPS), a serious gastrointestinal condition associated with gastrointestinal obstruction, according to a study in the August 21 issue of JAMA. Characteristics of this locus also suggest the possibility of an inverse relationship between levels of circulating cholesterol in neonates and IHPS risk.

21 Aug 2013

Trinity researchers reveal CHD5 protein acts as tumor suppressor in nervous system development

CHD5 has previously been proposed as a tumour suppressor, acting as a brake that prevents healthy cells from developing into cancer cells. But the part played by the protein in healthy tissue, and whether this role is important for its ability to counter tumour growth, has remained largely uncharted.

14 Aug 2013

Study reports high survival rates for children with rare subtype of leukaemia

A pioneering genetic study means that children with a rare subtype of leukaemia have 75% less chance of their leukaemia recurring.

13 Aug 2013

Bacterial strains that delay cell division might be used to design drugs that stop division entirely

In 1958 a group of scientists working in Denmark made the striking observation that bacterial cells are about twice as large when they are cultured on a rich nutrient source than when they are cultured on a meager one.

13 Aug 2013

Risk for childhood cancer moderately increased among adolescents with major birth defects

A multistate study led by researchers at the University of Utah has revealed that the risk for childhood cancer is moderately increased among children and young adolescents with certain types of major birth defects.

12 Aug 2013

Study: Immune-regulating molecules can trigger lymphomas

A small group of immune-regulating molecules, when overproduced even moderately, can trigger the blood cancers known as lymphomas, according to a new study led by scientists from The Scripps Research Institute (TSRI).

9 Aug 2013

Researchers unveil comprehensive portrait of the genome of world's first immortal cell line

A team from the University of Washington has unveiled a comprehensive portrait of the genome of the world's first immortal cell line, known as HeLa. The cell line was derived in 1951 from an aggressive cervical cancer that killed Henrietta Lacks, a 31-year-old African-American tobacco farmer and mother of five - the subject of the 2010 New York Times bestseller, The Immortal Life of Henrietta Lacks.

8 Aug 2013

Research findings may give scientists a way to destroy cancerous cells

Researchers at Warwick Medical School have identified the key role played by a team of proteins in the process of mitosis. Working out how to control them may give scientists a way to destroy cancerous cells.

8 Aug 2013

Cancer-linked mitosis: an interview with Professor Scott Kern, Johns Hopkins University School of Medicine

Mitosis is the process by which a cell gives rise to two daughter cells. It’s the basis behind the growth of the human body, the renewal of the human body as it ages, and unfortunately, the growth of cancers.

7 Aug 2013

Scientists reveal biochemical pathway responsible for manufacturing glycoalkaloids

In 1924, Science magazine reported on a fatal case of potato poisoning: James B. Matheney of Vandalia, Illinois, had gathered about one and a half bushels of tubers, which had turned green due to sunlight exposure.

1 Aug 2013

Researchers identify stem cells in urine can be directed to become multiple cell types

Could harvesting stem cells for therapy one day be as simple as asking patients for a urine sample? Researchers at Wake Forest Baptist Medical Center's Institute for Regenerative Medicine and colleagues have identified stem cells in urine that can be directed to become multiple cell types.

31 Jul 2013

Researchers study how human herpes virus packages genetic information during infection

An international collaboration of researchers including Felicia Goodrum of the University of Arizona's immunobiology department has studied how a human herpes virus carried by the majority of the population packages its genetic information during infection.

31 Jul 2013

Inhalable gene therapy may restore function of crucial enzyme to reverse deadly PAH

The deadly condition known as pulmonary arterial hypertension (PAH), which afflicts up to 150,000 Americans each year, may be reversible by using an inhalable gene therapy, report an international team of researchers led by investigators at the Cardiovascular Research Center at Icahn School of Medicine at Mount Sinai.

31 Jul 2013

Researchers to study knowledge and satisfaction of women who choose DNA prenatal screening test

A recently available DNA-based prenatal blood test used to screen pregnancies for Down syndrome and similar chromosome abnormalities in high-risk women is moving a step closer to use in the general pregnancy population.

From Natera 25 Jul 2013

Study results suggest reexamination of biological, medical importance of X chromosome

Painstaking new analysis of the genetic sequence of the X chromosome—long perceived as the "female" counterpart to the male-associated Y chromosome—reveals that large portions of the X have evolved to play a specialized role in sperm production.

24 Jul 2013

International Consortium receives grant to examine genetic reasons of schizophrenia in deletion syndrome patients

Today, the Royal College of Surgeons in Ireland (RCSI) will host a two day International Brain and Behaviour Consortium meeting on Chromosome 22q11.2 Deletion Syndrome (22q11.2DS).

24 Jul 2013

CLAMP: A newly discovered protein that regulates genes

They say a good man is hard to find. Were it not for a newly discovered protein, the X chromosome of a male fruit fly could never be found by a gene-regulating complex that male flies need to develop and survive. And that case is just one example of what the new finding means. More generally, the research provides biologists with a model of how proteins that govern gene transcription find their targets on chromosomes, a process that's essential to healthy cell function and sometimes implicated in disease.

22 Jul 2013

NKX2-8 mutation in dogs may be a risk factor for human neural tube defects, say researchers

A gene related to neural tube defects in dogs has for the first time been identified by researchers at the University of California, Davis, and University of Iowa.

20 Jul 2013

C. difficile bacteriophage provides new weapon to battle against superbugs

IFR microbiologists are reinvigorating a way of battling C. difficile infections that they hope will help overcome the growing problem of antibiotic resistant superbugs in hospitals.

19 Jul 2013

Discovery provides evidence that genetic defect responsible for Down syndrome can be suppressed

Scientists at the University of Massachusetts Medical School are the first to establish that a naturally occurring X chromosome "off switch" can be rerouted to neutralize the extra chromosome responsible for trisomy 21, also known as Down syndrome, a genetic disorder characterized by cognitive impairment.

18 Jul 2013

Chromosome X News and Research

Further Reading

Researchers identify genome-wide locus for serious gastrointestinal condition in infants

Trinity researchers reveal CHD5 protein acts as tumor suppressor in nervous system development

Study reports high survival rates for children with rare subtype of leukaemia

Bacterial strains that delay cell division might be used to design drugs that stop division entirely

Risk for childhood cancer moderately increased among adolescents with major birth defects

Study: Immune-regulating molecules can trigger lymphomas

Researchers unveil comprehensive portrait of the genome of world's first immortal cell line

Research findings may give scientists a way to destroy cancerous cells

Cancer-linked mitosis: an interview with Professor Scott Kern, Johns Hopkins University School of Medicine

Scientists reveal biochemical pathway responsible for manufacturing glycoalkaloids

Researchers identify stem cells in urine can be directed to become multiple cell types

Researchers study how human herpes virus packages genetic information during infection

Inhalable gene therapy may restore function of crucial enzyme to reverse deadly PAH

Researchers to study knowledge and satisfaction of women who choose DNA prenatal screening test

Study results suggest reexamination of biological, medical importance of X chromosome

International Consortium receives grant to examine genetic reasons of schizophrenia in deletion syndrome patients

CLAMP: A newly discovered protein that regulates genes

NKX2-8 mutation in dogs may be a risk factor for human neural tube defects, say researchers

C. difficile bacteriophage provides new weapon to battle against superbugs

Discovery provides evidence that genetic defect responsible for Down syndrome can be suppressed

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