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.
UCLA study characterizes brain differences between people with genetic risk for schizophrenia, autism

UCLA study characterizes brain differences between people with genetic risk for schizophrenia, autism

Research findings may provide answers for infertility in older women

Research findings may provide answers for infertility in older women

Sperm epigenetics and fertility

Sperm epigenetics and fertility

Weekly doses of steroids help hasten recovery in muscle injuries

Weekly doses of steroids help hasten recovery in muscle injuries

Study identifies first genetic locus for anorexia nervosa

Study identifies first genetic locus for anorexia nervosa

New technology could hold key to predicting outcome of blood cancer patients

New technology could hold key to predicting outcome of blood cancer patients

Study sheds light on neural mechanisms of Fragile X syndrome

Study sheds light on neural mechanisms of Fragile X syndrome

Discovery of protein that causes liver disease brings hope for new treatments

Discovery of protein that causes liver disease brings hope for new treatments

Researchers uncover molecule that may explain smoking-CHD connection

Researchers uncover molecule that may explain smoking-CHD connection

Researchers identify new antibiotic resistance gene in bacteria from dairy cows

Researchers identify new antibiotic resistance gene in bacteria from dairy cows

Scientists use stem cells to identify underlying cellular defects that cause Angelman syndrome

Scientists use stem cells to identify underlying cellular defects that cause Angelman syndrome

New test can quickly and accurately diagnose dangerous colistin-resistant bacteria

New test can quickly and accurately diagnose dangerous colistin-resistant bacteria

Collaboration between Hamilton Robotics and Illumina creates noninvasive streamlined prenatal testing solution

Collaboration between Hamilton Robotics and Illumina creates noninvasive streamlined prenatal testing solution

Seeing genes inside living cells

Seeing genes inside living cells

Scientists discover potential trigger for MDS in children with rare genetic disorder

Scientists discover potential trigger for MDS in children with rare genetic disorder

Study explains how genetic mutations linked to telomere capping complex contribute to cancers

Study explains how genetic mutations linked to telomere capping complex contribute to cancers

Illumina introduces fast, highly accurate Veriseq NIPT Solution in the European Union

Illumina introduces fast, highly accurate Veriseq NIPT Solution in the European Union

Organoids in cell culture dish offer new insights into development of the brain

Organoids in cell culture dish offer new insights into development of the brain

Researchers provide new insights into age-related female infertility

Researchers provide new insights into age-related female infertility

Experts report serious limitations to technology for screening embryos

Experts report serious limitations to technology for screening embryos