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.

Scientists identify biomarkers to predict patient’s response to breast cancer treatment

Why do some breast cancers respond to treatment while others resist it? A study led by researchers at the University of North Carolina Lineberger Comprehensive Cancer Center may provide insight into this important question.

8 Dec 2016

Alkaloid in ayahuasca beverage triggers neurogenesis in human neural cells

Ayahuasca is a beverage that has been used for centuries by Native South-Americans. Studies suggest that it exhibits anxiolytic and antidepressant effects in humans.

7 Dec 2016

Study highlights requirement of protein in initiation of apoptosis in uveal melanoma

New research from the University of Liverpool has identified the role of a specific protein in the human body that can help prevent the survival and spread of eye cancer, by initiating cancer 'cell-suicide'.

6 Dec 2016

Research findings point to inherited genetic basis of ALL risk in children

A late-breaking abstract being presented today during the 58th American Society of Hematology Annual Meeting and Exposition in San Diego identifies inherited genetic mutations in the gene IKZF1 that confer a higher likelihood of developing pediatric acute lymphocytic leukemia (ALL).

6 Dec 2016

Starvation may shorten lifespans of children and male descendants, study suggests

New Tel Aviv University research suggests that periods of fasting or starvation may significantly shorten the lifespans of both children and their male descendants.

5 Dec 2016

Scientists discover unique genomic changes integral to testicular cancer development

Researchers led by scientists at Dana-Farber Cancer Institute say they have identified unique genomic changes that may be integral to testicular cancer development and explain why the great majority are highly curable with chemotherapy - unlike most solid tumors.

1 Dec 2016

Protective barrier inside chromosomes helps prevent errors during cell division, study finds

Fresh insights into the structures that contain our genetic material could explain how the body's cells stay healthy.

1 Dec 2016

Scientists identify microrna that provides clues for quieting auditory hallucinations of schizophrenia

St. Jude Children's Research Hospital scientists have identified a small RNA (microRNA) that may be essential to restoring normal function in a brain circuit associated with the "voices" and other hallucinations of schizophrenia.

30 Nov 2016

Researchers engineer cells with 'built-in genetic circuit' that can inhibit tumour growth

Researchers at the University of Southampton have engineered cells with a 'built-in genetic circuit' that produces a molecule that inhibits the ability of tumours to survive and grow in their low oxygen environment.

24 Nov 2016

Scientists develop new technology that sheds light on HIV infection

A group of researchers at the Centre for Genomic Regulation and the Pompeu Fabra University in Barcelona, Spain, have developed a new technology that sheds light on the HIV infection and offers a first glance at the expression landscape of the HIV in the human genome.

23 Nov 2016

Einstein researcher receives $7.5 million NIH grant to study genetics of congenital heart disease

The National Institutes of Health has awarded Bernice Morrow, Ph.D., at Albert Einstein College of Medicine and collaborators at the Children's Hospital of Philadelphia a five-year, $7.5 million grant to study the genetics of congenital heart abnormalities.

22 Nov 2016

Study offers genetic explanation why cancer occurs commonly in males than females

In a new study, a group of Boston scientists, including researchers at Dana-Farber Cancer Institute, offer a genetic explanation for the age-old conundrum of why cancer is more common in males than females.

22 Nov 2016

Researchers create new Zika replicon system to find ways to combat virus

New research from The University of Texas Medical Branch in Galveston, in collaboration with Southwest University in Chongqing, China and the University of Leuven in Belgium, have developed a way to replicate the basic structure of the Zika virus, stripping it of the genes that make the virus infectious.

18 Nov 2016

Veterans Affairs researchers discover alleles of certain genes that offer protection from GWI

Veterans Affairs researchers have found that certain forms, or alleles, of a gene known to play a key role in the immune system appear to offer protection from Gulf War illness (GWI). Further, they discovered how such protection is manifested in the brain.

17 Nov 2016

Researchers create first mouse model for common form of infant leukemia

After nearly two decades of unsuccessful attempts, researchers from the University of Chicago Medicine and the Cincinnati Children's Hospital Medical Center have created the first mouse model for the most common form of infant leukemia.

15 Nov 2016

Length of telomeres may reveal if vitamin D and omega-3 supplements improve heart health, longevity

The length of your telomeres appears to be a window into your heart health and longevity, and scientists are measuring them to see if vitamin D and omega-3 supplements really improve both.

14 Nov 2016

UPCI scientists reveal how cancer cells hijack DNA repair pathways to stay alive

Research by scientists at the University of Pittsburgh Cancer Institute has revealed how cancer cells hijack DNA repair pathways to prevent telomeres, the endcaps of chromosomes, from shortening, thus allowing the tumor to spread. The findings are published today in the journal Cell Reports.

8 Nov 2016

UNC scientists find clue that may help explain why people differ in ability to survive arterial blockages

Researchers at the University of North Carolina School of Medicine have found a major clue that may explain why some people sustain relatively little damage from strokes or heart attacks despite severe arterial blockages.

7 Nov 2016

IU scientists find evidence for link between prostate cancer and Ewing's sarcoma

Medical researchers at Indiana University Bloomington have found evidence for a link between prostate cancer, which affects millions of men age 50 and older, and Ewing's sarcoma, a rare form of cancer that affects children and young adults.

25 Oct 2016

Small RNA molecules could contribute to serious pregnancy complication, study finds

A family of small RNA molecules affects the development of cells that give rise to the placenta - an organ that transfers oxygen and nutrients from mother to fetus -- in ways that could contribute to a serious pregnancy complication, UT Southwestern Medical Center researchers report.

24 Oct 2016