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.

APOE gene variant may be protective and prolong life, finds study

A new study of 38,537 persons of European ancestry suggests that a rare variation of a gene called APOE may be protective and prolong life, in sharp contrast to a more widely studied APOE variant that increases risk of death.

7 Aug 2019

Scientists use AI to recognize patterns in breast cancer

Scientists have used artificial intelligence to recognize patterns in breast cancer - and uncovered five new types of the disease each matched to different personalized treatments.

2 Aug 2019

Discovery of protective protein could open door to better treatment of fast-growing cancer cells

The discovery that an essential protein plays a protective role during cell division, could open the door to better targeted treatment of fast-growing cancer cells.

1 Aug 2019

Common feature that makes cancer cells appear bloated could be their potential weak spot

In a study using yeast cells and data from cancer cell lines, Johns Hopkins University scientists report they have found a potential weak spot among cancer cells that have extra sets of chromosomes, the structures that carry genetic material.

23 Jul 2019

Researchers reveal molecular cause for severe multi-organ disorder

Three unrelated families on three continents (from continental Portugal, the United States and Brazil), all with healthy ancestors, had children with a very rare disease.

18 Jul 2019

BU professor awarded NIH grant to study Down syndrome

Tarik F. Haydar, PhD, professor of anatomy and neurobiology at Boston University School of Medicine, has been awarded a two-year Exploratory/Developmental Research Grant Award (R21) from the National Institutes of Health.

16 Jul 2019

Exciting study shows how centrioles center the process of cell division

All life on earth depends upon the process of mitosis or cell division in which the chromosomal content of a cell is equally divided between two new cells.

12 Jul 2019

Research reveals genetic cause of deadly digestive disease in children

Nearly 10 years ago, a group of Israeli clinical researchers emailed Lawrence Berkeley National Laboratory (Berkeley Lab) geneticist Len Pennacchio to ask for his team's help in solving the mystery of a rare inherited disease that caused extreme, and sometimes fatal, chronic diarrhea in children.

11 Jul 2019

Researchers pinpoint treatment target for rare liver cancer in adolescents, young adults

New findings show how a genetically aberrant, fused protein promotes a rare form of liver cancer in adolescents and young adults. The researchers also saw that a certain mix of drugs could target the fused protein and the enzymes that it recruits.

10 Jul 2019

Targeted treatment offers symptom relief for patients with psychosis

Treatment for individuals who experience psychosis, such as hallucinations and delusions as a result of a psychiatric illness, can be targeted to a specific structural mutation, according to a study published by researchers from McLean Hospital and other institutions in the journal Biological Psychiatry.

3 Jul 2019

New study could change our understanding of how stem cells differentiate

A pioneering new study led by Florida State University biologists could fundamentally change our understanding of how embryonic stem cells differentiate into specific cell types.

24 Jun 2019

New mutation discovered in the leptin gene

The global obesity epidemic is so far-reaching it now has an overarching name: globesity. Texas Biomed Staff Scientist Raul Bastarrachea, M.D., is part of a team that discovered a new mutation in the gene that regulates the key hormone suppressing hunger called leptin.

22 Jun 2019

New genetic marker linked to higher risk of premenopausal breast cancer

University of Alberta researchers have added a new genetic marker to the breast cancer map, helping to expand the list of genetic mutations clinicians can watch for in cancer screenings.

20 Jun 2019

Study links high number of copies of chromosomal region to chemotherapeutic drug resistance

Researchers at the Bellvitge Biomedical Research Institute, with the participation of collaborators from the Baylor College of Medicine and the University Institute of Oncology of Asturias, publish today in Cancer Research a study where they relate the high number of copies of a chromosomal region with the appearance of resistance to a chemotherapeutic drug.

19 Jun 2019

Study uncovers potential modifier genes in patients with Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease is the most common inherited neurological disorder affecting peripheral motor and/or sensory nerves in humans.

18 Jun 2019

Research opens up new avenues for understanding the causes of schizophrenia

Schizophrenia causes hallucinations and memory or cognition problems inter alia. This psychiatric illness affects 0.5% of the general population, and it may be related to genetic abnormalities of chromosome 22, known as 22q11 deletion syndrome.

17 Jun 2019

Researchers find salmonella resistant to antibiotics of last resort in the U.S.

Researchers from North Carolina State University have found a gene that gives Salmonella resistance to antibiotics of last resort in a sample taken from a human patient in the U.S. The find is the first evidence that the gene mcr-3.1 has made its way into the U.S. from Asia.

13 Jun 2019

Researchers identify new sarcoma familial risk gene

A team of WA researchers has uncovered new genes that could play an important role in the development of sarcoma, a group of rare bone, muscle and connective tissue cancers.

12 Jun 2019

Researchers identify genetic factor linked to development of diabetic peripheral neuropathy

Researchers from Joslin Diabetes Center, using a genome-wide association study, have identified a genetic factor linked to the development of diabetic peripheral neuropathy.