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.

'Deep sequencing' technology identifies new target area for depression

Scientists at the Texas Biomedical Research Institute and Yale University have identified a new target area in the human genome that appears to harbor genes with a major role in the onset of depression.

29 Oct 2011

Scientists discover Leishmania parasite with juggling chromosomes

Scientists found a deadly parasite with some of its chromosomes in duplicate, others in triplicate, while still others are present four or even five times. Moreover, the copy number varies between individuals. Such a bizarre occurrence has never before been found in nature, in any organism. As a rule, chromosomes should come in couples. The scientists, from the Institute of Tropical Medicine (ITG) and the Wellcome Trust Sanger Institute, made the striking discovery while deciphering the genetic code of a series of Leishmania-parasites.

29 Oct 2011

New discoveries on drug resistance in Leishmania

Two remarkable discoveries were today revealed by researchers into genome analysis of Leishmania parasites. These results uncovered a surprising level of variation at the genome structure level.

28 Oct 2011

C21orf91 gene associated with susceptibility to herpes simplex labialis

Investigators have identified a human chromosome containing a specific gene associated with susceptibility to herpes simplex labialis (HSL), the common cold sore.

28 Oct 2011

A more accurate blood test to detect fetal Downs syndrome launched

Pregnant mothers in the U.S. who wish to know whether they're carrying a fetus with Down syndrome now have access to a commercial genetic blood test that has a 99 per cent accuracy rate.

20 Oct 2011

Scientists discover complex cell mechanism that becomes an obstacle for radiation effectiveness

Researchers from Massachusetts General Hospital, Harvard Medical School and CIC bioGUNE discover a complex cell mechanism activated by a protein —HOXB9— that becomes an obstacle for radiation effectiveness.

20 Oct 2011

New sequencing method can identify genetic variants linked to ASD

Geneticists at Emory University School of Medicine have demonstrated a method that enables the routine amplification of all the genes on the X chromosome. The technology allows the rapid and highly accurate sequencing and identification of novel genetic variants affecting X chromosome genes.

19 Oct 2011

JPO issues new patent for Genprex's lead lung cancer candidate

A new patent covering tumor suppression technologies, including the company's lead product candidate Oncoprex, was recently awarded to The University of Texas System by the Japan Patent Office. Patent number 4813746 pertains to the discovery that chromosome 3p21.3 genes act as cancer suppressors.

19 Oct 2011

New DNA-based prenatal blood test can identify pregnancy with Down syndrome

A new DNA-based prenatal blood test that can strikingly reduce the number of risky diagnostic procedures needed to identify a pregnancy with Down syndrome is ready to be introduced into clinical practice.

18 Oct 2011

Two genetic variants associated with increased susceptibility to severe dengue

Researchers in South East Asia have identified two genetic variants associated with increased susceptibility to severe dengue. The study, funded by the Wellcome Trust and the Agency for Science, Technology, and Research, Singapore, offers clues to how the body responds to dengue infection.

18 Oct 2011

Raw fruits and veggies may offset genetic risk for heart disease: Study

In a new study a team of researchers looked at the genotypes of 27,243 people from two separate studies to see if they had a certain gene variant. Earlier studies including a 2010 meta-analysis in the Journal of the American Medical Assn. found that the 9p21 gene is associated with a higher risk of heart attack and cardiovascular disease.

13 Oct 2011

ASHG to honor U of U geneticist with William Allan Award

As a teenager just moved to Iowa from war-ravaged Germany in 1951, John M. Opitz, M.D., wanted to study developmental biology, but his "very Prussian" mother insisted he go to medical school instead.

12 Oct 2011

CHOP, Albert Einstein College of Medicine to study genetics of conotruncal defects

The Eunice Kennedy Shriver National Institute of Child Health & Human Development, part of the National Institutes of Health, has awarded researchers at Albert Einstein College of Medicine of Yeshiva University and collaborators at the Children's Hospital of Philadelphia (CHOP) a five-year, $6.7 million grant to study the genetics of both rare and common congenital heart abnormalities known as conotruncal defects.

12 Oct 2011

Genetics & IVF Institute now offers 24 Chromosome Microarray

The Genetics & IVF Institute is now offering 24 Chromosome Microarray, which is a new, comprehensive test used as part of an IVF cycle to evaluate the number of chromosomes present in an embryo before it is transferred to the mother.

11 Oct 2011

Scientists identify 16M SNPs that associate with risk of gout, serum uric acid levels

Scientists at deCODE Genetics and academic collaborators from Iceland, Norway, Denmark, the Netherlands and the USA report the discovery of low frequency variants in the human genome that associate with risk of gout, a common inflammatory arthritis, and serum uric acid levels.

10 Oct 2011

Study identifies three new chromosomal regions implicated in susceptibility to melanoma

The genomic analysis technologies enable the study of genetic factors related to numerous diseases. In few areas this researches brought such a big and useful volume of information as in the case of melanoma.

10 Oct 2011

Researchers identify unusual genomic architecture linked with very severe forms of disease

When cells divide normally, DNA gets copied perfectly and distributed among the daughter cells with an even hand. Occasionally though, DNA breaks during division and is rearranged, resulting in duplications or deletions of important parts of the blueprint.

3 Oct 2011

Researchers develop HTGTS to map translocatome in the genome

Researchers at Children's Hospital Boston and the Immune Disease Institute (IDI) have created a method for mapping "hot spots" in the genome where chromosomes are most likely to break and recombine, knowledge that helps define the rules that govern when and where breaks occur.

30 Sep 2011

GWAS uncovers new genes associated with type 1 diabetes

The largest-ever analysis of genetic data related to type 1 diabetes has uncovered new genes associated with the common metabolic disease, which affects 200 million people worldwide. The findings add to knowledge of gene networks involved in the origin of this complex disorder, in which patients depend on frequent insulin injections to control their blood sugar levels.

30 Sep 2011

New technique helps identify how RNA molecules control gene expression

A new technique developed by researchers at the Stanford University School of Medicine allows researchers to identify the exact DNA sequences and locations bound by regulatory RNAs. This information is necessary to understand how the recently identified RNA molecules control the expression of neighboring and distant genes.

30 Sep 2011