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 causative gene for features of 2q32q33 microdeletion syndrome

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24 Aug 2009

Inc. magazine ranks Signature Genomic Laboratories no.1012 on its fastest-growing private companies ranking list

Inc. magazine ranked Signature Genomic Laboratories no. 1012 on its third annual Inc. 5000, an exclusive ranking of the nation's fastest-growing private companies. The company, which performs microarray-based diagnostic genetic testing of chromosome abnormalities in individuals with unexplained mental retardation and/or birth defects, experienced three-year sales growth of 302.9%, more than twice that of the Inc. 5000 industry median and over 12 times the industry benchmark. Signature was also ranked 70th of companies in the healthcare sector.

21 Aug 2009

More evidence that genes increase a smokers' risk of lung cancer

Cancer Research UK funded scientists have confirmed that inherited changes in certain regions of the genome can increase a smokers' risk of developing lung cancer lung cancer, and determine the type of lung cancer that develops. Their results were published in this week's edition of the journal Cancer Research*.

21 Aug 2009

Bayer Crop Science uses Chromatin's proprietary mini-chromosome technology

Chromatin Inc. and Bayer CropScience announced today that they have entered into a technological alliance and license agreement to use Chromatin’s proprietary mini-chromosome technology for crop improvement.

20 Aug 2009

Discovery of inherited gene variants that account for 37 percent of childhood acute lymphoblastic leukemia

Scientists at St. Jude Children’s Research Hospital have identified inherited variations in two genes that account for 37 percent of childhood acute lymphoblastic leukemia (ALL), including a gene that may help predict drug response.

16 Aug 2009

Protein plays unexpected role protecting chromosome tips

A protein specialist that opens the genomic door for DNA repair and gene expression also turns out to be a multi-tasking workhorse that protects the tips of chromosomes and dabbles in a protein-destruction complex, a team lead by researchers at The University of Texas M. D. Anderson Cancer Center reports in the Aug. 13 edition of Molecular Cell.

13 Aug 2009

Discovery of genetic mutations that increase risk of schizophrenia

In collaboration with colleagues from across Europe, researchers from the University of Copenhagen and the Mental Health Services in the Capital Region of Denmark have found mutations in the human genome that lead to an increased risk of developing schizophrenia.

11 Aug 2009

Decode Genetics announces Q2 2009 financials

deCODE genetics (Nasdaq: DCGN) today announced its consolidated financial results for the quarter ended June 30, 2009. A conference call to discuss these results and recent developments in the company's business will be webcast live tomorrow, Tuesday, August 11, at 8:00am Eastern Daylight Time/12 noon GMT/1pm British Summer Time (details below).

10 Aug 2009

Unlikely genetic suspect implicated in Dandy-Walker malformation

A genetic search that wound its way from patients to mouse models and back to patients has uncovered an unlikely gene critically involved in a common birth defect which causes mental retardation, motor delays and sometimes autism, providing a new mechanism and potentially improving treatment for the disorder.

9 Aug 2009

Discovery of possible mechanisms to protect against genetic alterations, diseases

Peering into the DNA of tiny yeast, researchers at the Moores Cancer Center at the University of California, San Diego and the San Diego Branch of the Ludwig Institute for Cancer Research have pinpointed a large number of genes that can prevent a type of genetic rearrangement that may lead to cancer and other diseases.

6 Aug 2009

Smoking marijuana has toxic effects on cells

In a finding that challenges the increasingly popular belief that smoking marijuana is less harmful to health than smoking tobacco, researchers in Canada are reporting that smoking marijuana, like smoking tobacco, has toxic effects on cells.

6 Aug 2009

Protein DNA repair complex key to avoiding DNA repair mistakes

As the body creates antibodies to fight invaders, a three-protein DNA repair complex called MRN is crucial for a normal gene-shuffling process to proceed properly, University of Michigan research shows.

5 Aug 2009

New insight into human ciliopathy

In the September 1st issue of G&D, Dr. Karen Oegema (UCSD) and colleagues identify the molecular basis of the lethal developmental disorder, hydrolethalus syndrome, and reveal that hydrolethalus syndrome actually belongs to the emerging class of human ciliopathy diseases.

4 Aug 2009

Genetic link to ovarian cancer found

Scientists have located a region of DNA which - when altered - can increase the risk of ovarian cancer according to research published in Nature Genetics today.

3 Aug 2009

Discovery of key event in prostate cancer progression

A study led by researchers at the Ohio State University Comprehensive Cancer Center and Dana-Farber Cancer Institute reveals how late-stage, hormone-independent prostate tumors gain the ability to grow without need of hormones.

24 Jul 2009

National Institutes of Health develops research plan on Fragile X syndrome and associated disorders

The National Institutes of Health has developed a research plan to advance the understanding of fragile X syndrome and its associated conditions, fragile X-associated tremor/ataxia syndrome and fragile X-associated primary ovarian insufficiency. Fragile X syndrome causes intellectual and developmental disabilities and results from a mutation in a gene on the X chromosome.

20 Jul 2009

New research tool – map of genomic variation for diagnosing and identifying genetic problems

Genetics researchers have unveiled a powerful new resource for scientists and health providers studying human illnesses -- a reference standard of deletions and duplications of DNA found in the human genome. Drawn from over 2,000 healthy persons, the study provides one of the deepest and broadest sets of copy number variations (CNVs) available to date, along with a new research tool for diagnosing and identifying genetic problems in patients.

15 Jul 2009