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.

Neanderthal gene makes people susceptible to COVID-19, but protects against HIV

A study recently published in the top-tier journal Proceedings of the National Academy of Sciences of the United States of America (PNAS) shows how a specific gene flow from Neandertals can act as a double-edged sword by increasing the risk for the development of severe coronavirus disease 2019 (COVID-19), and at the same time decreasing the risk for the infection with the human immunodeficiency virus (HIV).

23 Feb 2022

Surprising discovery about genetic form of microcephaly has potential to inform treatment strategies

Virginia Tech researchers publishing in the Journal of Medical Genetics made a discovery about a genetic form of microcephaly -- a condition where babies' heads and brains are smaller and grow more slowly than those of unaffected children.

14 Feb 2022

Researchers identify autoantibody targets in COVID-19 patients

In a new study, researchers have been investigating auto-immune responses to natural human antigens in COVID-19 patients.

14 Feb 2022

Drugs used to increase insulin signaling may be effective therapeutic strategy for autism

Drugs to increase insulin signaling may be effective for treating autism say Lancaster University researchers, who have discovered how a genetic change impacts on insulin signaling and glucose metabolism in the brain.

10 Feb 2022

Genetically informed brain atlases help identify hundreds of genomic loci

An international team of scientists has used atlases of the human brain informed by genetics to identify hundreds of genomic loci. Loci is plural for locus, and in genetics indicates the physical location of a gene or variant on a chromosome.

7 Feb 2022

Genomes of marine invertebrates found to be surprisingly stable across deep time

Scientists have discovered that the genomes of marine invertebrates have been surprisingly stable across deep time.

6 Feb 2022

Using interdisciplinary approach to beat cancer

European Cooperation in Science and Technology (COST) World Cancer Day aims at raising awareness of cancer and to encourage its prevention, detection, and treatment.

4 Feb 2022

Study offers unprecedented insight into the mechanism of action of topo VI enzyme

The function of an enzyme, critical to most forms of life, has been revealed.

2 Feb 2022

UofL professor wins $6.7 million grant to investigate how metals cause lung cancer

For nearly three decades, John Pierce Wise Sr. has investigated the connection between exposure to metals and cancer, working both in the lab and in the field, reporting significant discoveries about the effects of metals on chromosomes in lung cancer and how those effects differ in humans and in whales.

27 Jan 2022

Low-cost test could open new avenues for earlier diagnosis, treatment of rare genetic disorders

A newly developed test to screen for three rare genetic disorders simultaneously in newborns was feasible, reliable and scalable, according to a new study.

24 Jan 2022

Exploring loss of Y chromosome in white blood cells as a risk-factor of life-threatening COVID-19 in men

Researchers published a study exploring the possibilities of predisposing men for a life-threatening disease course of COVID-19.

24 Jan 2022

Researchers identify first known patients with BUB1 biallelic mutations

A new study published in Science Advances described the first two patients known to have mutations in both copies of BUB1, a critical gene for cell division.

20 Jan 2022

New method reverses insecticide resistance using CRISPR/Cas9 technology

Insecticides play a central role in efforts to counter global impacts of mosquito-spread malaria and other diseases, which cause an estimated 750,000 deaths each year. These insect-specific chemicals, which cost more than $100 million to develop and bring to market, also are critical to controlling insect-driven damage on crops that poses a challenge to food security.

18 Jan 2022

New pathways responsible for hepatocellular carcinoma identified

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer. It is one of leading causes of cancer-related deaths globally, with more than 700,000 new cases and 600,000 estimated HCC deaths each year.

18 Jan 2022

Overall survival rate has nearly doubled for Ph+ ALL patients after hematopoietic stem cell transplant

For patients with acute lymphoblastic leukemia (ALL) carrying the Philadelphia chromosome and whose disease relapsed after allogeneic hematopoietic stem cell transplantation (HCT), the two-year overall survival rate has nearly doubled from the period between 2000 and 2004 to the period between 2015 and 2019.

13 Jan 2022

Scientists discover a division of labor between genetic switches

Two X chromosomes are actually one too many. Female mammalian cells hence switch off one of them – but only when the cells start to specialize into tissues.

5 Jan 2022

Deletion of autism-linked gene diminishes myelin in mice

Myelin, a sheath of insulation around nerves that enables electrical impulses to efficiently travel through the central nervous system, is diminished in mice that have a gene deletion associated with autism spectrum disorder, new research finds.

21 Dec 2021

Study reveals chromosome-level changes that relate to drug resistance in melanoma

Precision therapies targeting melanoma and other cancers have improved patient survival, but tumors often stop responding to drugs, and recent studies point to changes in DNA – both inside and outside chromosomes – as a driving factor in tumor genesis as well as in treatment resistance.

20 Dec 2021

Correlation between idiopathic pulmonary fibrosis and COVID-19

A new study investigates the genetic overlap between COVID-19 and idiopathic pulmonary fibrosis to identify possible shared biological mechanisms.

14 Dec 2021

Drug combination without chemotherapy can be effective in treating older patients with Ph+ ALL

The combination of dasatinib, blinatumomab, and prednisone can be effective in treating older patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL) who are not good candidates for intensive chemotherapy treatment.

13 Dec 2021