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.

Full assembly of human chromosome 8 reveals novel genes, disease risks

The full assembly of human chromosome 8 is reported this week in Nature. While on the outside this chromosome looks typical, being neither short nor long or distinctive, its DNA content and arrangement are of interest in primate and human evolution, in several immune and developmental disorders, and in chromosome sequencing structure and function generally.

8 Apr 2021

Mother's stress levels during conception could be a determinant of fetal sex

A study carried out by scientists from the University of Granada has revealed that women who experience stress both before becoming pregnant and during conception are almost twice as likely to have a girl as a boy.

6 Apr 2021

New genetic link to male infertility found

The findings published in eLife show that men with this unstable subtype of the Y chromosome have a significantly increased risk of genomic rearrangements.

1 Apr 2021

SwRI researchers part of two collaborative teams receive SAMF bioscience grants

Collaborative teams that include Southwest Research Institute staff received two of six recently awarded San Antonio Medical Foundation (SAMF) bioscience grants. SwRI, in collaboration with UT Health San Antonio and University Health System, received a nearly $200,000 grant to develop machine learning algorithms for cancer detection.

31 Mar 2021

Rare genetic variant may explain severe COVID-19 in young healthy male patients

A recent study describes the association of rare alleles in a specific gene with severe COVID-19 in young male patients.

29 Mar 2021

New approach can help identify patients at risk for esophageal cancer

A combination of esophageal brushing and extensive genetic sequencing of the sample collected can detect chromosome alterations in people with Barrett's Esophagus, identifying patients at risk for progressing to esophageal cancer, according to a new study by researchers at the Johns Hopkins Kimmel Cancer Center and Case Western Reserve University.

29 Mar 2021

New method for scDNA sequencing provides insights into breast cancer evolution

vercoming previous technical challenges with single-cell DNA (scDNA) sequencing, a group led by researchers at The University of Texas MD Anderson Cancer Center has developed a novel method for scDNA sequencing at single-molecule resolution.

24 Mar 2021

Study reveals a genetic variant linked to COVID-19 severity in young men

A study of young men with COVID-19 has revealed a genetic variant linked to disease severity.

23 Mar 2021

New technique may result in earlier and easier identification of patients with Barrett's esophagus

A new technique for sampling and testing cells from Barrett's esophagus (BE) patients could result in earlier and easier identification of patients whose disease has progressed toward cancer or whose disease is at high risk of progressing toward cancer, according to a collaborative study by investigators at Case Western Reserve University and Johns Hopkins Kimmel Cancer Center (JHKCC).

23 Mar 2021

Male fertility and androgen production may be impacted by COVID-19

An interesting new study has appeared online in the journal Hormones that discusses the effects of COVID-19 on the male and female gonads.

22 Mar 2021

Insights into elusive protein complex can help find novel treatments for chromosomal disorders

The cells in our body are constantly fighting off the threat of cancer by repairing damaged DNA. In a new study, scientists from Tokyo University of Science investigate the structure of an elusive protein complex that plays a key role in the activation of the "Fanconi anemia pathway" involved in DNA repair, and report on the factors governing its stability.

17 Mar 2021

UVA researcher developing innovative gene therapy to help children with Rett syndrome

A University of Virginia School of Medicine scientist is developing an innovative gene therapy she hopes will slow disease progression and improve movement, coordination and communication in children with Rett syndrome.

17 Mar 2021

Chromatin-regulating enzyme found to be a key driver of common lung cancer

A chromatin-regulating enzyme has been shown by in-depth interdisciplinary investigations to be a key driver of a common type of lung cancer. Drugs that target the enzyme could improve treatment and survival rates for this particular cancer.

15 Mar 2021

MGH researchers uncover new clues about X chromosome inactivation

Researchers at Massachusetts General Hospital have uncovered new clues that add to the growing understanding of how female mammals, including humans, "silence" one X chromosome.

15 Mar 2021

Novel computer-guided design tool helps increase the efficiency of cell conversions

There is a great need to generate various types of cells for use in new therapies to replace tissues that are lost due to disease or injuries, or for studies outside the human body to improve our understanding of how organs and tissues function in health and disease.

13 Mar 2021

VEXAS syndrome in men is more common than previously thought

A rare disease first identified in 2020 is much more common than first thought, say researchers at the University of Leeds investigating its origins.

11 Mar 2021

Genetics can partly explain aggressive behavior in children with ADHD with DBDs

An international collaboration headed by researchers from iPSYCH has found genetic variants that increase the risk of aggression in children with ADHD.

11 Mar 2021

Whole genome sequencing may guide blood cancer treatment

For certain blood cancers, such as acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), deciding whether patients need an aggressive treatment typically hinges on a set of lab tests to identify genetic changes.

11 Mar 2021

Researchers identify human BCAS3 and C16orf70 as novel autophagic proteins

Autophagy is an intracellular degradation process of cytosolic materials and damaged organelles. Researchers at Ubiquitin Project of TMIMS have been studying the molecular mechanism of mitophagy, the selective autophagy process to eliminate damaged mitochondria.

5 Mar 2021