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 develop new method for producing image of individual DNA molecules' genetic make-up

A completely new method for producing an image of individual DNA molecules' genetic make-up has been developed by researchers in Sweden and Denmark. The results are published in the latest issue of the journal Proceedings of the National Academy of Sciences of the USA (PNAS).

19 Jul 2010

Olig1 and Olig2 genes are associated with Down syndrome, scientists identify

Down syndrome is a well known cause of mental retardation and other medical problems, including early onset of Alzheimer disease. It has long been known that Down syndrome is associated with an individual having an additional copy of chromosome 21. Research findings reported in the July 18 advanced online publication of Nature Neuroscience have narrowed down the critical genetic elements responsible for some aspects of Down syndrome.

19 Jul 2010

AMPK may regulate epigenetic mechanism: Research

AMP-activated protein kinase, or AMPK, is a master regulator protein of metabolism that is conserved from yeast to humans. When a cell is low on fuel, AMPK shuts down processes that use energy and turns on processes that produce energy.Biologists have been studying how AMPK works for several decades and know that once it is activated, AMPK turns on a large number of genes by passing the "make more energy" message through numerous signaling cascades in the cell. What was not known, until now, was that AMPK also works via an epigenetic mechanism to slow down or stop cell growth.

17 Jul 2010

Susceptibility to Behcet's disease associated with genes involved in body's immune response

Researchers with the National Institutes of Health have found susceptibility to Behcet's disease, a painful, inflammatory condition, to be associated with genes involved in the body's immune response.

14 Jul 2010

Asuragen, Life Technologies announce European launch of BCR/ABL1 Quant Test

Asuragen, Inc. and Life Technologies Corporation announced today that they have achieved CE-marking and commercial launch in Europe of the BCR/ABL1 Quant™ Test, Asuragen's clinically validated and cGMP manufactured test intended to aid clinicians in the monitoring and treatment of individuals afflicted with chronic myeloid leukemia (CML). Asuragen manufacturers the monitoring test, which is exclusively distributed by Life Technologies and runs on the company's Applied Biosystems CE-marked 7500 Fast Dx Real-Time PCR Instrument™.

13 Jul 2010

Researchers identify genetic variant associated with increased risk of AAA

Geisinger researchers are part of an international team that has identified a genetic variant more common in individuals with abdominal aortic aneurysms. This is one of the largest studies ever into the genetics of AAA. The results of the work will appear in this week's online edition of Nature Genetics.

13 Jul 2010

Common SNP in sequence of human genome conferring risk of vascular diseases discovered

Scientists at deCODE genetics and academic colleagues from the Netherlands and twelve other countries across Europe and North America today report the discovery of a common single-letter variation (SNP) in the sequence of the human genome conferring risk of a range of vascular diseases. The SNP confers risk of abdominal aortic aneurysm (AAA), early-onset heart attack, peripheral artery disease (PAD), and pulmonary embolism, independent of other known risk factors.

12 Jul 2010

Study identifies a region in human genome that is linked to FSGS

An in-depth study of a family with multiple generations affected by kidney disease has identified a previously unknown location for a gene abnormality causing focal segmental glomerulosclerosis, according to a study appearing in an upcoming issue of the Journal of the American Society of Nephrology.

9 Jul 2010

Scientists identify potential disease genes in humans and mice

An international consortium of scientists of Helmholtz Zentrum München and the University of Toronto has identified previously unknown potential disease genes in humans and mice. Genes on the X chromosome, which regulate embryonic development, are the focus of the current publication in the renowned journal Genome Research. Men have only one X chromosome, and therefore mutations on this chromosome disproportionately affect males, frequently leading to serious diseases such as hemophilia, muscular dystrophy and mental retardation.

7 Jul 2010

Study finds EPB41L3 'protector gene' inactivated in 65% of ovarian cancers

A new gene that normally protects against ovarian cancer is switched-off in two-thirds of cases of the disease, reveals a study published in the journal Neoplasia today.

3 Jul 2010

Researchers identify gene abnormality for most common congenital birth defect, clubfoot

Although clubfoot is one of the most common congenital birth defects, few genetic causes have been found. Now, researchers at Washington University School of Medicine in St. Louis have found what they believe to be the most common cause of inherited clubfoot yet discovered.

2 Jul 2010

AMP comments on array-based cytogenetic tests at FDA's public meeting

Today, the Association for Molecular Pathology presented comments at the US Food & Drug Administration's public meeting on array-based cytogenetic tests. The FDA convened the meeting to seek answers to more than a dozen questions they had on how to evaluate the performance, interpret results and report findings of array-based cytogenetic tests for copy number variation.

1 Jul 2010

Secondhand smoke exposure during pregnancy causes permanent genetic damage in newborns

Newborns of non-smoking moms exposed to secondhand smoke during pregnancy have genetic mutations that may affect long-term health, according to a University of Pittsburgh Graduate School of Public Health study published online in the Open Pediatric Medicine Journal. The abnormalities, which were indistinguishable from those found in newborns of mothers who were active smokers, may affect survival, birth weight and lifelong susceptibility to diseases like cancer.

1 Jul 2010

Rubicon Genomics' PicoPlex linear WGA technology proves effective in clinical study

Rubicon Genomics today announced that its PicoPlex linear whole genome amplification technology was proven to be effective in an independent clinical study organized by the European Society for Human Reproduction and Embryology. At a press conference during its 26th Annual Meeting in Rome, ESHRE reported the success of its "groundbreaking proof of principle study" showing that a new approach incorporating PicoPlex could more accurately detect and characterize chromosomal abnormalities in human eggs.

1 Jul 2010

Simple blood test may help detect chromosomal abnormalities in developing foetus

Researchers in The Netherlands believe they are on the verge of developing a simple, prenatal blood test that would be able to detect accurately chromosomal abnormalities in the developing foetus.

29 Jun 2010

Telomere length could prove a quality marker for embryonic development

Scientists from the University of Warwick and University Hospitals Coventry and Warwickshire NHS Trust, are the first to directly measure a specific region of DNA in human embryos. The length of this region could be a quality marker for embryonic development.

29 Jun 2010

Non-Invasive prenatal blood test to detect chromosomal abnormalities in foetus

Researchers in The Netherlands believe they are on the verge of developing a simple, prenatal blood test that would be able to detect accurately chromosomal abnormalities in the developing foetus. At present, the only reliable way to do this is through amniocentesis or chorionic villus sampling, both of which are invasive and carry the risk of triggering a miscarriage.

29 Jun 2010

Scientists use PGS method to analyse chromosomal status of eggs

The efficacy of preimplantation genetic screening has been one of the most hotly disputed subjects in assisted reproduction over the past few years. The European Society of Human Reproduction and Embryology PGS Task Force has now shown, in its groundbreaking proof of principle study, that screening of polar bodies (small cells that are the by-product of egg development), is a reliable method to analyse the chromosomal status of an egg.

28 Jun 2010

12 new gene variants that impact individual's risk of developing type 2 diabetes identified

An international consortium including Helmholtz Zentrum München and the German Diabetes Center, Düsseldorf has identified 12 new gene variants which impact the individual's risk of developing type 2 diabetes. The study represents a major contribution towards elucidating the complex pathogenesis of this important widespread disease. Nature Genetics has published the findings of this study in its current issue.

28 Jun 2010

Scientists uncover variations in X chromosome inactivation in early passages of female embryonic stem cells

Human embryonic stem cells hold great promise for studying and treating disease and for the practice of regenerative medicine. However, more must be learned to ensure the cells that may one day be transplanted into humans are safe.

28 Jun 2010

Chromosome X News and Research

Further Reading

Researchers develop new method for producing image of individual DNA molecules' genetic make-up

Olig1 and Olig2 genes are associated with Down syndrome, scientists identify

AMPK may regulate epigenetic mechanism: Research

Susceptibility to Behcet's disease associated with genes involved in body's immune response

Asuragen, Life Technologies announce European launch of BCR/ABL1 Quant Test

Researchers identify genetic variant associated with increased risk of AAA

Common SNP in sequence of human genome conferring risk of vascular diseases discovered

Study identifies a region in human genome that is linked to FSGS

Scientists identify potential disease genes in humans and mice

Study finds EPB41L3 'protector gene' inactivated in 65% of ovarian cancers

Researchers identify gene abnormality for most common congenital birth defect, clubfoot

AMP comments on array-based cytogenetic tests at FDA's public meeting

Secondhand smoke exposure during pregnancy causes permanent genetic damage in newborns

Rubicon Genomics' PicoPlex linear WGA technology proves effective in clinical study

Simple blood test may help detect chromosomal abnormalities in developing foetus

Telomere length could prove a quality marker for embryonic development

Non-Invasive prenatal blood test to detect chromosomal abnormalities in foetus

Scientists use PGS method to analyse chromosomal status of eggs

12 new gene variants that impact individual's risk of developing type 2 diabetes identified

Scientists uncover variations in X chromosome inactivation in early passages of female embryonic stem cells

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