Chromosome X News and Research

RSS

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 of new mechanism for cell division

A Swedish research group, partly financed by NWO, has discovered a new mechanism for cell division in a microorganism found in extremely hot and acidic conditions.

25 Nov 2008

Researchers urge physicians to test for fragile X gene mutations in patients of all ages

Writing in this week's Journal of the American Medical Association , UC Davis M.I.N.D. Institute researchers urge physicians to test for mutations of the fragile X gene in patients of all ages.

25 Nov 2008

Genetic variation for persons with diabetes linked to greater risk of coronary artery disease

Patients with type 2 diabetes who have poor glycemic control and a certain genetic variation have an increased risk of coronary artery disease, according to a study in the November 26 issue of JAMA, the Journal of the American Medical Association.

25 Nov 2008

Scientists discover an important new layer of regulation in the cell division cycle

A Florida State University College of Medicine research team led by Yanchang Wang has discovered an important new layer of regulation in the cell division cycle, which could lead to a greater understanding of the way cancer begins.

21 Nov 2008

Common ADHD drugs do not cause genetic damage in children

In contrast to recent findings, two of the most common medications used to treat attention deficit hyperactivity disorder (ADHD) do not appear to cause genetic damage in children who take them as prescribed, according to a new study by researchers at the National Institutes of Health (NIH) and Duke University Medical Center.

19 Nov 2008

Scientists discover new compounds to target muscular dystrophy

Using a drug-discovery technique in which molecules compete against each other for access to the target - the strand of toxic RNA that causes the most common form of muscular dystrophy in adults - a team at the University of Rochester Medical Center has identified several compounds that, in the laboratory, block the unwanted coupling of two molecules that is at the root of the disease.

19 Nov 2008

Link found between cryptorchidism and genetic mutations

A small percentage of males born with cryptorchidism (failure of one or both testicles to descend into the scrotum), the most frequent congenital birth defect in male children, are more likely to have genetic mutations, including for a syndrome that is a common genetic cause of infertility, according to a study in the November 19 issue of JAMA .

18 Nov 2008

Microarray analysis improves prenatal diagnosis

A "chip" or array that can quickly detect disorders such as Down syndrome or other diseases associated with chromosomal abnormalities proved an effective tool in prenatal diagnosis in a series of 300 cases at Baylor College of Medicine, said researchers in a report that appears in the current issue of the journal Prenatal Diagnosis.

17 Nov 2008

Protein enzyme BubR1 provides new understanding of processes behind cancer-cell survival and drug-resistance

A study of how one protein enzyme, BubR1, helps make sure chromosomes are equally distributed during mitosis might explain how the process of cell division goes so awry in cancer, according to researchers from Fox Chase Cancer Center.

17 Nov 2008

Astragalus root plant chemical used to fight HIV

Like other kinds of cells, immune cells lose the ability to divide as they age because a part of their chromosomes known as a telomere becomes progressively shorter with cell division.

11 Nov 2008

Newborn neurons in the adult brain can settle in the wrong neighborhood

In a study that could have significant consequences for neural tissue transplantation strategies, researchers at the Salk Institute for Biological Studies report that inactivating a specific gene in adult neural stem cells makes nerve cells emerging from those precursors form connections in the wrong part of the adult brain.

11 Nov 2008

Data expands the clinical utility of deCODE tests for heart attack, atrial fibrillation and stroke

Several presentations by deCODE genetics scientists and independent researchers at the American Heart Association Scientific Sessions 2008 being held at the New Orleans Convention Center from November 8 to12 are expected to expand upon the clinical utility of evaluating individual risk of heart attack, or atrial fibrillation and stroke, respectively, by measuring the genetic markers that are the basis of the deCODE MI and deCODE AF tests.

11 Nov 2008

Researchers discover genetic basis for some common congenital birth defects

10 Nov 2008

Absence of ERK2 gene linked to birth defects

A multidisciplinary research team at Case Western Reserve University led by Gary Landreth, Ph.D., a professor in the School of Medicine's Department of Neurosciences, has uncovered a common genetic pathway for a number of birth defects that affect the development of the heart and head. Abnormal development of the jaw, palate, brain and heart are relatively common congenital defects and frequently arise due to genetic errors that affect a key developmental pathway.

10 Nov 2008

Researchers unravel mysteries of brain aneurysms

Yale researchers have taken the first critical steps in unraveling the mysteries of brain aneurysms, the often fatal rupturing of blood vessels that afflicts 500,000 people worldwide each year and nearly killed Vice President-elect Joseph Biden two decades ago.

10 Nov 2008