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.

Novel Structure Proteins (NSP) could help predict the possibility of tumor growth in a patient

A new family of genes called Novel Structure Proteins (NSP) discovered by researchers in the Sbarro Institute for Cancer Research and Molecular Medicine in Temple University’s College of Science and Technology could have the potential for predicting the possibility of tumor growth in a patient.

9 Jan 2005

New genetic clues provide better understanding of epilepsy

Two specific areas in chromosome 7 and chromosome 16 have been associated with photosensitivity, an epilepsy-related trait, by a team of European scientists in the January issue of Human Molecular Genetics.

5 Jan 2005

Direct modulation of progesterone signaling appears to influence ovarian cancer risk

A woman's risk of ovarian cancer rises significantly if she carries either of two previously unexamined variations in the gene that codes for the progesterone receptor, according to a team of researchers led by scientists from the Keck School of Medicine of the University of Southern California.

5 Jan 2005

Genomics tools provide clues to what causes 400 million cases of gastrointestinal disease each year

In a study that could benefit medical and food-safety research, scientists have used comparative genomics tools to find clues about why some strains of the bacterium Campylobacter – which each year cause more than 400 million cases of gastrointestinal disease – are more virulent than others.

4 Jan 2005

Needling chromosomes yields insights into cell division

By impaling individual chromosomes with glass needles one thousandth the diameter of a human hair, a Duke University graduate student has tested their "stickiness" to one another during cell division. Her uncanny surgical skills have added a piece to the large and intricate puzzle of how one cell divides into two -- a process fundamental to all organisms.

23 Dec 2004

Mutant gene that starves the brain of serotonin 10 times more prevalent in depressed patients

A mutant gene that starves the brain of serotonin, a mood-regulating chemical messenger, has been discovered and found to be 10 times more prevalent in depressed patients than in control subjects, report researchers funded by the National Institutes of Health’s National Institute of Mental Health (NIMH) and National Heart Lung and Blood Institute (NHLBI).

21 Dec 2004

Blocking gene's activity may control deadly skin cancer without harming normal cells

Researchers at Dana-Farber Cancer Institute and Children's Hospital Boston have discovered that malignant melanoma, the potentially lethal skin cancer, can't grow without a steady supply of a protein that normal cells can do without.

20 Dec 2004

Rett Syndrome, the first identified epigenetic disease - linked to specific defects in the three-dimensional folding of chromatin

Sometime between the age of 6 and 18 months, after a period of seemingly normal development, girls affected with Rett Syndrome lose interest in play; they gradually become withdrawn and anxious, develop autistic-like behaviors, and acquire specific symptoms like repetitive teeth-grinding and hand-wringing.

20 Dec 2004

New advances in sickle cell disease

Excruciating pain episodes, recurrent pneumonias, strokes, severe infections, chronic hemolytic anemia, and secondary pulmonary hypertension are common complications of sickle cell disease, a life-threatening inherited defect in blood that causes normally disc-shaped red blood cells to take on a sickle shape.

6 Dec 2004

Important genetic risk factor for amyotrophic lateral sclerosis

Two Hershey, Pa., researchers were part of a team that has uncovered what may be an important genetic risk factor for amyotrophic lateral sclerosis (ALS).

6 Dec 2004

Episome vectors offer fresh angle to gene therapy

A European research team is seeking to overcome the early setbacks suffered by the promising new field of ‘gene therapy’ by developing a revolutionary delivery technique, known as ‘episome vectors’. This breakthrough could pave the way to treating hereditary diseases by injecting the body with healthy versions of damaged genes.

6 Dec 2004

Study shows long-term benefits for chronic myeloid leukemia patients receiving therapy with imatinib

CHU in Poitiers, France, yesterday announced results of a study showing that newly diagnosed patients with a certain form of leukemia who are treated early with imatinib are more likely to achieve complete cytogenetic responses (the elimination of leukemic cells, a major goal of therapy) and have improved long-term outcomes.

6 Dec 2004

Genetic mutations and cellular modifications may provide clues to the associations between slight genetic abnormalities and often fatal diseases

Modern research is delving deep into the human genome to find the answers to medical mysteries and, hopefully, cures for the most deadly diseases. According to four new studies presented during the 46th Annual Meeting of the American Society of Hematology

5 Dec 2004

Researchers step closer to cure for common childhood cancer

Acute lymphoblastic leukemia (ALL) is a malignant disease caused by the abnormal growth and development of white blood cells (WBC) in the bone marrow and blood. ALL is the most common cancer occurring in children with an annual rate of approximately 30 to 40 new cases per million.

5 Dec 2004

Researchers find mutations in a multifunctional protein cause Parkinsonism

A team of researchers at Mayo Clinic in Jacksonville, Fla. and colleagues in Canada and Germany have discovered a gene and six mutations of it that cause symptoms associated with Parkinson's disease and other neurodegenerative disorders.

18 Nov 2004

70% of cases of spina bifida are preventable by folic-acid supplementation

A seminar in this week’s issue of THE LANCET discusses the causes, symptoms, and treatments relating to spina bifida, and reinforces an important public-health message for women about to become pregnant

18 Nov 2004

Sex genes of infectious fungus closely resemble human Y chromosome

Fungi and animals, including humans, have a lot in common when it comes to the arrangement of genes that determine their sex, according to new work by Howard Hughes Medical Institute geneticists at the Duke University Medical Center.

10 Nov 2004

Discovery of new gene that protects against lung cancer

Cancer Research UK scientists have discovered a new gene that protects against lung cancer, according to a study published in the journal PNAS.

9 Nov 2004

Search for genetic key to corneal disease

A new federal grant focusing on painful inherited visual disorders that scar the cornea will allow researchers to narrow the genetic cause of one type of corneal dystrophy and to offer improved diagnosis of this family of diseases.

8 Nov 2004

Researchers find two locations in the human genome that may harbor genes that increase the risk of Alzheimer’s disease

Researchers at Columbia University Medical Center have found two locations in the human genome that may harbor genes that increase the risk of Alzheimer’s disease. If confirmed, they will be the first genes linked to Alzheimer’s disease since ApoE4 was discovered in 1993.

8 Nov 2004

Chromosome X News and Research

Further Reading

Novel Structure Proteins (NSP) could help predict the possibility of tumor growth in a patient

New genetic clues provide better understanding of epilepsy

Direct modulation of progesterone signaling appears to influence ovarian cancer risk

Genomics tools provide clues to what causes 400 million cases of gastrointestinal disease each year

Needling chromosomes yields insights into cell division

Mutant gene that starves the brain of serotonin 10 times more prevalent in depressed patients

Blocking gene's activity may control deadly skin cancer without harming normal cells

Rett Syndrome, the first identified epigenetic disease - linked to specific defects in the three-dimensional folding of chromatin

New advances in sickle cell disease

Important genetic risk factor for amyotrophic lateral sclerosis

Episome vectors offer fresh angle to gene therapy

Study shows long-term benefits for chronic myeloid leukemia patients receiving therapy with imatinib

Genetic mutations and cellular modifications may provide clues to the associations between slight genetic abnormalities and often fatal diseases

Researchers step closer to cure for common childhood cancer

Researchers find mutations in a multifunctional protein cause Parkinsonism

70% of cases of spina bifida are preventable by folic-acid supplementation

Sex genes of infectious fungus closely resemble human Y chromosome

Discovery of new gene that protects against lung cancer

Search for genetic key to corneal disease

Researchers find two locations in the human genome that may harbor genes that increase the risk of Alzheimer’s disease

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