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.

In-depth sequencing of SARS-CoV-2 variants crucial in controlling outbreaks

In this interview, News-Medical speaks to Professor Dana Crawford about her research efforts during the COVID-19 pandemic.

2 Aug 2021

Scientists uncover genetics involved in COVID-19 induced respiratory failure

A new genetic study from an international team of scientists has uncovered genes involved in severe coronavirus disease 2019 (COVID-19) illness.

27 Jul 2021

SARS-CoV-2 reprograms host chromatic network to induce immune dysfunction

A recent study conducted at the University of Texas Science Center, Houston, in the USA, has revealed that upon infection, SARS-CoV-2 alters the host chromatin architecture to suppress antiviral interferon-responsive genes and augment inflammatory genes. The study is currently available on the bioRxiv* preprint server.

22 Jul 2021

MET amplification identified as a potentially actionable driver for non-small cell lung cancer

A study led by D. Ross Camidge, MD, PhD, director of thoracic oncology at the University of Colorado School of Medicine and CU Cancer Center member, has helped to define MET amplification as a rare but potentially actionable driver for non-small cell lung cancer (NSCLC).

20 Jul 2021

Transient chromosomal errors can spur the formation of tumors, study finds

A Ludwig Cancer Research study has found that inducing random chromosome instability (CIN) events in mice for as little as one week is enough to trigger harmful chromosomal patterns in cells that spur the formation of tumors.

16 Jul 2021

Researchers discover new genetic driver of autism and other developmental disorders

A research group including Kobe University's Professor TAKUMI Toru (also a Senior Visiting Scientist at RIKEN Center for Biosystems Dynamics Research) and Assistant Professor TAMADA Kota, both of the Physiology Division in the Graduate School of Medicine, has revealed a causal gene (Necdin, NDN) in autism model mice that have the chromosomal abnormality called copy number variation.

9 Jul 2021

Optical genome mapping could change the existing workflow within cytogenetic laboratories

Dutch-French research shows that Optical Genome Mapping (OGM) detects abnormalities in chromosomes and DNA very quickly, effectively and accurately. Sometimes even better than all existing techniques together, as they describe in two proof-of-concept studies published in the American Journal of Human Genetics.

8 Jul 2021

Study: Gene editing therapy for early-stage Huntington’s disease may have long-lasting benefits

In a new study on mice, Johns Hopkins Medicine researchers report that using MRI scans to measure blood volume in the brain can serve as a noninvasive way to potentially track the progress of gene editing therapies for early-stage Huntington's disease, a neurodegenerative disorder that attacks brain cells.

7 Jul 2021

Rare genetic variants have a big impact on the risk of developing type 2 diabetes

Scientists at the University of Cambridge have identified rare genetic variants - carried by one in 3,000 people - that have a larger impact on the risk of developing type 2 diabetes than any previously identified genetic effect.

7 Jul 2021

Study unravels the link between chromosomal instability and cellular senescence

Chromosomal instability is a feature of solid tumours such as carcinoma. Likewise, cellular senescence is a process that is highly related to cellular ageing and its link to cancer is becoming increasingly clear. Scientists led by ICREA researcher Dr. Marco Milán at IRB Barcelona have revealed the link between chromosomal instability and cellular senescence.

7 Jul 2021

New discovery provides clues to elucidate the pathogenesis of muscle diseases

A research collaboration based in Kumamoto University, Japan has discovered that muscles and the resident stem cells (satellite cells) responsible for muscle regeneration retain memory of their location in the body.

6 Jul 2021

A new study reveals unintended CRISPR/Cas9 editing events

A recent study by researchers from Sweden and the United Kingdom shows that CRISPR/Cas9-based genomic engineering can prompt unwanted on-target effects, and highlights the complexity of human DNA repair mechanisms in the presence of the powerful prokaryotic Cas9 nuclease. The paper is currently available on the bioRxiv* preprint server.

4 Jul 2021