Chromosome X News and Research

RSS

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.

MicroRNAs play an important role in human cancer

Over the past few years, scientists have discovered that a new class of genetic regulators called "microRNAs" influences normal human growth and development. Now, researchers have found that microRNAs also play an important role in human cancer. The findings are published in today's issue of the journal Nature (June 9).

9 Jun 2005

Researchers link aberrant 'microRNA' expression to human cancer

8 Jun 2005

New understanding of microRNAs

Ribonucleic acid, or RNA, has long been thought to be important only to translate a gene's DNA into the proteins that are cells' workhorses. But new evidence shows that tiny bits of RNA not used to make proteins actually play central roles in normal biology and in the development of cancers.

8 Jun 2005

Study is the first to identify involvement of chromosome 21 in developmental regression autism

A new Cincinnati Children's Hospital Medical Center study links regions of two chromosomes to susceptibility for a type of autism characterized by regression in development. Developmental regression can include the loss of previously acquired language, social skills or both.

8 Jun 2005

Computer simulation helps understand DNA transcription process

New York University chemists have employed a computer simulation whose results have enhanced scientific understanding of the DNA transcription process. The study, funded by the National Institutes of Health, appears in the June 7 issue of the Proceedings of the National Academy of Sciences.

5 Jun 2005

Scientists have uncovered the structure of a network of proteins that help regulate the life cycle of cells

Scientists at Memorial Sloan-Kettering Cancer Center (MSKCC) have uncovered the structure of a network of proteins that help regulate the life cycle of cells. Understanding the network's physical layout is an important step toward learning its precise function, and in finding ways to correct flaws in the system that could lead to cancer.

2 Jun 2005

The bacteria that cause food poisoning, bubonic plague, and whooping cough all deploy the same weapon to infect the body

A molecular "syringe" sticks out of the bacteria, pokes a hole in a nearby cell, and squirts in venomous proteins that hijack the cell's machinery.

2 Jun 2005

Bald men can blame mum!

Despite an enormous range of treatments, obscure lotions and tinctures there appears to be very few successful counter-measures for hair loss in men. Beginning with receding hairlines, every second man suffers from hair loss to some degree, and it has always been suspected that hereditary factors are important in causing hair loss.

22 May 2005

Deletion on chromosome 11q may guide decision to use chemotherapy for neuroblastoma

When genes are deleted on a particular section of chromosome 11, the result is an aggressive form of the childhood cancer neuroblastoma. A new study suggests that detecting this genetic deletion during the initial evaluation of children with neuroblastoma may indicate to physicians that they should recommend a more aggressive regimen of chemotherapy to fight the cancer.

16 May 2005

Scientists take aim at virulent bacteria by decoding machinery of key control enzyme

By deciphering the ingenious mechanism used by a particular enzyme to modify bacterial chromosome chemistry, scientists have come a step closer to designing a new kind of drug that could stop virulent bacterial infections in their tracks. Their research will be published in the May 6 issue of the journal Cell.

5 May 2005

Mosaic Analysis with Double Markers (MADM) - A powerful new tool to study diseases and genetics

A powerful laboratory technique used by fruit fly geneticists for more than a decade is now available to scientists studying genes and diseases in mice.

5 May 2005

Researchers make new advances in determining the structure of all possible DNA sequences

Oregon State University researchers have made significant new advances in determining the structure of all possible DNA sequences – a discovery that in one sense takes up where Watson and Crick left off, after outlining in 1953 the double-helical structure of this biological blueprint for life.

3 May 2005

Age-related macular degeneration is triggered, possibly by an infection

Age-related macular degeneration, the leading cause of blindness in the elderly, occurs when a common inherited gene variation is triggered, possibly by an infection, according to a new study led by researchers at Columbia University Medical Center and the University of Iowa, with an international research team.

1 May 2005

Pollutants appear to have an affect on sex chromosome

A team of researchers from Lund University in Sweden have found that exposure to a class of environmental pollutants can change the ratio of sperm carrying male and female chromosomes.

1 May 2005

Family history DNA sleuths run risk of uncovering infertility

A simple DNA test that is available commercially to help people establish their ancestry could in fact disclose male infertility claims a new study from the University of Leicester.

28 Apr 2005

Abnormal cell division explained

Why do some cancer cells divide not into two, as cells are supposed to do in mitosis, but into three-four new cells that look thoroughly abnormal? This question was raised as early as the 1890s by the German tumor researcher David Hansemann, who could observe the strange mitosis even using the microscopes of his day. Now another David, Lund University researcher David Gisselsson, has found an answer.

28 Apr 2005

Increasing benefit seen in novel drug AMN107, that treats Gleevec resistance

An investigational drug is producing powerful responses in patients resistant to Gleevec, the targeted therapy that helps most people diagnosed with chronic myeloid leukemia (CML), an international research team headed by investigators at The University of Texas M. D. Anderson Cancer Center is reporting.

23 Apr 2005

Enzyme that helps trigger the development of leukemia

Scientists at the University of North Carolina at Chapel Hill have identified an enzyme that helps trigger the development of leukemia, a cancer of blood cells.

21 Apr 2005

New gene linked to familial cancer

Scientists have identified a new gene that appears to be linked to a small but significant percentage of familial cancer cases – as well as seemingly randomly occurring malignancies.

20 Apr 2005

Fifteen-year hunt uncovers gene behind pseudothalidomide syndrome

A team of scientists from Colombia, the United States and elsewhere has successfully completed a 15-year-plus search for the genetic problems behind the very rare Roberts syndrome, whose physical manifestations often include cleft lip and palate and shortened limbs that resemble those of babies whose mothers took thalidomide during pregnancy.

11 Apr 2005