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.

Study sheds new light on why most bone marrow transplant patients suffer acute GVHD

A team of scientists led by a bone marrow transplant researcher at Fred Hutchinson Cancer Research Center has shed new light on why most bone marrow transplant patients who receive tissue-matched cells from unrelated donors still suffer acute graft-versus-host disease (GVHD).

6 Sep 2012

Researchers discover two gene variants that raise risk of pediatric cancer neuroblastoma

Researchers have discovered two gene variants that raise the risk of the pediatric cancer neuroblastoma. Using automated technology to perform genome-wide association studies on DNA from thousands of subjects, the study broadens understanding of how gene changes may make a child susceptible to this early childhood cancer, as well as causing a tumor to progress.

5 Sep 2012

FDA approves Bosulif to treat chronic myelogenous leukemia

The U.S. Food and Drug Administration today approved Bosulif (bosutinib) to treat chronic myelogenous leukemia (CML), a blood and bone marrow disease that usually affects older adults.

5 Sep 2012

Concentration increase of HUWE1 protein leads to intellectual disability

2 to 3 % of the children are born with an intellectual disability. Possibly by a genetic defect, but in 80% of these cases, we do not know - yet - which genes are responsible. VIB researchers at KU Leuven show that increased production of the HUWE1 protein is the cause in some patients.

31 Aug 2012

Researchers identify several genetic factors linked to C-reactive protein

African Americans have higher blood levels of a protein associated with increased heart-disease risk than European Americans, despite higher "good" HDL cholesterol and lower "bad" triglyceride levels. This contradictory observation now may be explained, in part, by a genetic variant identified in the first large-scale, genome-wide association study of this protein involving 12,000 African American and Hispanic American women.

31 Aug 2012

Scientists establish genetic mouse model for primary ovarian insufficiency

Scientists have established a genetic mouse model for primary ovarian insufficiency (POI), a human condition in which women experience irregular menstrual cycles and reduced fertility, and early exposure to estrogen deficiency.

31 Aug 2012

Quest Diagnostics announces availability of TERC test for cervical cancer

Quest Diagnostics, the world's leading provider of diagnostic testing, information and services, today announced the availability of a new laboratory test that identifies molecular changes to cervical cells that increase the likelihood a woman may develop cervical cancer.

From Quest Diagnostics 31 Aug 2012

Oral lesion progression markers validated, discovered

Loss of heterozygosity can reliably differentiate between individuals with premalignant oral lesions who are likely to progress to oral carcinoma, and those who are not, show study results.

30 Aug 2012

FISH assay identifies only few lung cancer patients who could benefit from crizotinib

Break apart a couple worm-like chromosomes and they may reconnect with mismatched tips and tails - such is the case of the EML4-ALK fusion gene that creates 2-7 percent of lung cancers. Almost exactly a year ago, the FDA approved the drug crizotinib to treat these ALK+ lung cancer patients, who were likely never smokers. Informed doctors use the test called a FISH assay to check for the EML4-ALK fusion gene, and then if the test is positive, ALK+ patients benefit greatly from crizotinib.

29 Aug 2012

People with guanine version of rs55705857 SNP more likely to develop gliomas

People who carry a "G" instead of an "A" at a specific spot in their genetic code have roughly a six-fold higher risk of developing certain types of brain tumors, a Mayo Clinic and University of California, San Francisco study has found. The

27 Aug 2012

New method can differentiate between breast cancer patients with good and poor prognosis

It is now possible to identify aggressive breast cancers by interpreting the mathematical patterns in the cancer genome. Researchers at the University of Oslo, Norway (UiO) have developed a completely new method for differentiating between breast cancer patients with high and low risks of dying from the illness.

24 Aug 2012

MOZ protein could explain variations in severity of DiGeorge syndrome

The discovery of a 'switch' that modifies a gene known to be essential for normal heart development could explain variations in the severity of birth defects in children with DiGeorge syndrome.

24 Aug 2012

Genetic key to severe malaria resistance uncovered

Researchers have identified two genetic variants linked with human resistance to severe malaria.

21 Aug 2012

Walnuts optimize male fertility

Eating walnuts on a daily basis seems to improve the quality of men’s sperm, show study findings.

20 Aug 2012

ARIAD initiates multi-center ponatinib Phase 1/2 clinical trial for CML in Japan

ARIAD Pharmaceuticals, Inc. today announced the initiation of a multi-center Phase 1/2 clinical trial in Japan of ponatinib, the Company's investigational BCR-ABL inhibitor.

20 Aug 2012

Walnuts provide key nutrients that may be essential in male reproductive health

Research published in the recent issue of Biology of Reproduction Papers-in-Press reports that 75 grams (approximately 2.5 ounces) of walnuts consumed per day improved sperm vitality, motility, and morphology (normal forms) in a group of healthy young men between 21-35 years of age.

17 Aug 2012

Passenger deletions that deactivate essential genes provide new opportunity to strike cancer

Genomic deletions promote cancer by carving up or eliminating tumor-suppressor genes, but now scientists report in the journal Nature that the collateral damage they inflict on neighboring genes exposes cancer cells to vulnerabilities and new avenues for attack.

16 Aug 2012

Pediatric imatinib for Philadelphia-chromosome ALL fights relapse

Trial findings confirm the benefits of imatinib therapy in children with Philadelphia-chromosome-positive acute lymphoblastic leukemia.

15 Aug 2012

Scientists identify new genetic alterations underlying high-risk subtype of ALL

Scientists have identified new genetic alterations underlying a high-risk subtype of the most common childhood cancer that could be effectively targeted with existing leukemia therapies.

14 Aug 2012

Researchers discover gene mutations linked to spinocerebellar ataxia

A global hunt for the cause of a crippling inherited nerve disorder has found its target. The discovery opens the door for better diagnosis and treatment of this particular disease - but also for better understanding of why nerves in the brain's movement-controlling center die, and how new DNA-mapping techniques can find the causes of other diseases that run in families.

13 Aug 2012