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.

Discovery offers much needed information about how virulent insect-borne diseases cause infection

For decades, scientists have thought the bacteria that cause the bubonic plague hijack host cells at the site of a fleabite and are then taken to the lymph nodes, where the bacteria multiply and trigger severe disease. But UNC School of Medicine researchers discovered that this accepted theory is off base. The bacteria do not use host cells; they traffic to lymph nodes on their own and not in great numbers.

16 Feb 2015

Scientists find seven new genes that can cause X-linked intellectual disability

X-linked intellectual disability is a disorder that predominantly affects men and can have highly variable clinical manifestations. Scientists at the Max Planck Institute for Molecular Genetics in Berlin have found seven new genes that can cause this genetic disease: Mutations of these genes on the X chromosome lead to various forms of intellectual disability.

15 Feb 2015

Longer donor leukocyte telomere length linked to improved survival following HCT

Among patients with severe aplastic anemia who received stem cell transplant from an unrelated donor, longer leukocyte (white blood cells) telomere length (a structure at the end of a chromosome) was associated with increased overall survival at 5 years, according to a study in the February 10 issue of JAMA.

12 Feb 2015

UNC researchers create new research tool to help crack the histone code

University of North Carolina scientists have created a new research tool, based on the fruit fly, to help crack the histone code. This research tool can be used to better understand the function of histone proteins, which play critical roles in the regulation of gene expression in animals and plants.

11 Feb 2015

Duke University researchers devise new method to activate genes with light

Duke University researchers have devised a method to activate genes in any specific location or pattern in a lab dish with the flip of a light switch by crossing a bacterium's viral defense system with a flower's response to sunlight.

9 Feb 2015

Researchers develop quality assurance tool for genome editing

A research team at Boston Children's Hospital's Program in Cellular and Molecular Medicine has developed a quality assurance tool for scientists using genome-editing technologies like the increasingly popular CRISPR. The assay, called high throughput genome translocation sequencing (HTGTS), rapidly gauges—for any given gene—these technologies' accuracy and their risk for causing potentially dangerous genomic collateral damage.

9 Feb 2015

Vanderbilt researchers find link between the biological clock and Angelman syndrome

Monitoring participants' biological clocks may be the quickest way to determine the effectiveness of experimental drugs currently under development to treat Angelman syndrome: a debilitating genetic disorder that occurs in more than one in every 15,000 live births.

6 Feb 2015

Researchers identify genetic variants associated with psoriatic arthritis

PsA is a common form of inflammatory form of arthritis causing pain and stiffness in joints and tendons that can lead to joint damage. Nearly all patients with PsA also have skin psoriasis and, in many cases, the skin disease is present before the arthritis develops. However, only one third of patients with psoriasis will go on to develop PsA.

5 Feb 2015

Cell free DNA analysis less effective than sequential screening in finding fetal chromosomal abnormalities

In a study to be presented on Feb. 5 in an oral plenary session at 8 a.m. PST, at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, in San Diego, researchers will report that cell free DNA analysis is less effective than sequential screening as primary testing for fetal chromosomal abnormalities.

5 Feb 2015

Alzheimer's brains commonly have many neurons with more DNA and genomic copies of APP gene

Scientists at The Scripps Research Institute have found diverse genomic changes in single neurons from the brains of Alzheimer's patients, pointing to an unexpected factor that may underpin the most common form of the disease.

5 Feb 2015

Genomics of papillary thyroid carcinoma (PTC): an interview with Professor Thomas J. Giordano

There are two types of thyroid cells and therefore there are two broad types of thyroid cancer. Medullary carcinoma is derived from parafollicular or C cells, whereas follicular cells give rise to several types of thyroid cancers.

4 Feb 2015

Study could lead to potential therapeutic targets to treat Ewing Sarcoma

A University of Colorado Cancer Center study published in the journal PLoS One finds alterations in expression of genes PIK3R3 and PTEN, more commonly observed in adult tumors, in the rare, young-adult bone cancer Ewing Sarcoma, potentially offering ways to improve therapy.

4 Feb 2015

OGT study explores successful adoption of CytoSure ISCA array at Sheffield Children's NHS Foundation Trust

Oxford Gene Technology, The Molecular Genetics Company, explores how Sheffield Children's NHS Foundation Trust has seamlessly transferred to its CytoSure ISCA 8x60k platform, in a new case study entitled Evaluating and switching to CytoSure microarrays. As the result of a highly stringent National Health Service tender for the supply of oligo-based cytogenetics research arrays, CytoSure was selected based on the quality of data and analysis software.

From Oxford Gene Technology 4 Feb 2015

Researchers reveal new pathway for inhibiting growth of tumor cells tied to BRCA mutations

Inhibiting the action of a particular enzyme dramatically slows the growth of tumor cells tied to BRCA1 and BRCA2 genetic mutations which, in turn, are closely tied to breast and ovarian cancers, according to researchers at NYU Langone Medical Center.

3 Feb 2015

Emory researchers complete detailed maps of 184 duplications found in genomes

Copy number variations (deletions or duplications of large chunks of the genome) are a major cause of birth defects, intellectual disability, autism spectrum disorder and other developmental disorders. Still, geneticists can definitively say how a CNV, once discovered in someone's DNA, leads to one of these conditions in just a fraction of cases.

31 Jan 2015

Cypher Genomics, Sequenom sign development agreement for noninvasive prenatal tests

Cypher Genomics, Inc., the leading genome informatics company, and Sequenom, Inc., the leading molecular diagnostics company, today announced a development agreement for next generation noninvasive prenatal tests (NIPT).

22 Jan 2015

Study identifies gene that may become resistant to current testicular cancer treatments

A major research study has uncovered several new genetic mutations that could drive testicular cancer - and also identified a gene which may contribute to tumours becoming resistant to current treatments.

22 Jan 2015

ASCB honors UTSA adjunct professor with E. B. Wilson Medal

William Brinkley, adjunct professor of biology in the UTSA College of Sciences, was recently honored with the E. B. Wilson Medal from the American Society for Cell Biology. The medal, the organization's highest honor for far-reaching contributions to cell biology over a lifetime in science, was presented to Brinkley at the 54th Annual Meeting in Philadelphia.

22 Jan 2015

Researchers gain new insight into fragile X syndrome

Scientists have gained new insight into fragile X syndrome -- the most common cause of inherited intellectual disability -- by studying the case of a person without the disorder, but with two of its classic symptoms.

17 Jan 2015

TERT mutations may make smokers more susceptible to emphysema

Mutations in a gene that helps repair damaged chromosome ends may make smokers — especially female smokers — more susceptible to emphysema, according to results of a new study led by Johns Hopkins Kimmel Cancer Center researchers.

14 Jan 2015

Chromosome X News and Research

Further Reading

Discovery offers much needed information about how virulent insect-borne diseases cause infection

Scientists find seven new genes that can cause X-linked intellectual disability

Longer donor leukocyte telomere length linked to improved survival following HCT

UNC researchers create new research tool to help crack the histone code

Duke University researchers devise new method to activate genes with light

Researchers develop quality assurance tool for genome editing

Vanderbilt researchers find link between the biological clock and Angelman syndrome

Researchers identify genetic variants associated with psoriatic arthritis

Cell free DNA analysis less effective than sequential screening in finding fetal chromosomal abnormalities

Alzheimer's brains commonly have many neurons with more DNA and genomic copies of APP gene

Genomics of papillary thyroid carcinoma (PTC): an interview with Professor Thomas J. Giordano

Study could lead to potential therapeutic targets to treat Ewing Sarcoma

OGT study explores successful adoption of CytoSure ISCA array at Sheffield Children's NHS Foundation Trust

Researchers reveal new pathway for inhibiting growth of tumor cells tied to BRCA mutations

Emory researchers complete detailed maps of 184 duplications found in genomes

Cypher Genomics, Sequenom sign development agreement for noninvasive prenatal tests

Study identifies gene that may become resistant to current testicular cancer treatments

ASCB honors UTSA adjunct professor with E. B. Wilson Medal

Researchers gain new insight into fragile X syndrome

TERT mutations may make smokers more susceptible to emphysema

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