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.

RMANJ releases new fertility checklist for early diagnosis and treatment options

With over seven million men and women in the United States impacted by infertility, information about early diagnosis and various infertility treatment options like in vitro fertilization (IVF), preimplantation genetic diagnosis (PGD), and comprehensive chromosome screening (CCS) can offer help to many patients looking to overcome infertility.

22 Apr 2014

Researchers reveal connection between Down syndrome and acute lymphoblastic leukemia

Although doctors have long known that people with Down syndrome have a heightened risk of developing acute lymphoblastic leukemia (ALL) during childhood, they haven't been able to explain why. Now, a team of Dana-Farber Cancer Institute investigators has uncovered a connection between the two conditions.

21 Apr 2014

Study sheds light on how extra chromosome 21 upsets equilibrium of entire genome in Down syndrome

Occurring in about one per eight hundred births, Down syndrome - or trisomy 21 - is the most frequent genetic cause of intellectual disability. It results from a chromosomal abnormality where cells of affected individuals contain a third copy of chromosome 21 (1% of the human genome).

18 Apr 2014

Genetic evidence confirms role of group of virus-fighting genes in cancer development

Researchers have found a major piece of genetic evidence that confirms the role of a group of virus-fighting genes in cancer development.

15 Apr 2014

Two candidate mTOR therapy biomarkers identified in RCC

Two genes, TSC1 and MTOR, warrant further investigation as biomarkers for treatment benefit with rapalogs in patients with renal cell carcinoma, indicate study results published in Clinical Cancer Research.

14 Apr 2014

Comprehensive genomic analysis of low-grade brain tumors sorts into three categories

Comprehensive genomic analysis of low-grade brain tumors sorts them into three categories, one of which has the molecular hallmarks and shortened survival of glioblastoma multiforme, the most lethal of brain tumors, researchers reported at the American Association for Cancer Research Annual Meeting 2014.

10 Apr 2014

Stressful upbringings can leave imprints on genes of African American children

Stressful upbringings can leave imprints on the genes of children as young as age 9, according to a study led by Princeton University and Pennsylvania State University researchers. Such chronic stress during youth leads to physiological weathering similar to aging.

10 Apr 2014

Scientists uncover surprising link between brain development and gene tied to breast cancer

Scientists at the Salk Institute have uncovered details into a surprising-and crucial-link between brain development and a gene whose mutation is tied to breast and ovarian cancer.

9 Apr 2014

Study examines links between parental obesity and risk of autism developmental in child

Several studies have looked at possible links between maternal obesity during pregnancy and the risk of developmental disorders in the child. However, paternal obesity could be a greater risk factor than maternal obesity, according to a new study from the Norwegian Institute of Public Health.

8 Apr 2014

Researchers generate 3D model of human malaria parasite genome

A research team led by a cell biologist at the University of California, Riverside has generated a 3D model of the human malaria parasite genome at three different stages in the parasite's life cycle - the first time such 3D architecture has been generated during the progression of the life cycle of a parasite.

7 Apr 2014

New research shows obesity is linked to our ability to digest carbohydrates

New research indicates that obesity in the general population may be genetically linked to how our bodies digest carbohydrates.

1 Apr 2014

Otsuka inks agreement with Eisai to acquire rights to hematological cancer treatment Dacogen

Otsuka Pharmaceutical Co., Ltd. has announced an agreement with Eisai Inc., a U.S. subsidiary of Eisai Co., Ltd. to acquire rights to the hematological cancer treatment Dacogen and to an enzyme inhibitor, E7727.

31 Mar 2014

Study suggest that women are resistant to mutations that contribute to autism

It takes more mutations to trigger autism in women than in men, which may explain why men are four times more likely to have the disorder, according to a study published 26 February in the American Journal of Human Genetics1.

25 Mar 2014

Rare abnormality in chromosomes increases risk of rare childhood leukaemia

Researchers have found that people born with a rare abnormality of their chromosomes have a 2,700-fold increased risk of a rare childhood leukaemia. In this abnormality, two specific chromosomes are fused together but become prone to catastrophic shattering.

24 Mar 2014

Scientists unlock one of mysteries of modern genetics

Scientists at Indiana University have unlocked one of the mysteries of modern genetics: how acquired traits can be passed between generations in a process called epigenetic inheritance. The new work finds that cells don't know to silence some genes based on information hardwired into their DNA sequences, but recognize heritable chemical marks that are added to the genes. These chemical tags serve as a form of molecular memory, allowing cells to recognize the genes and remember to silence them again in each new generation.

21 Mar 2014

Two new risk loci for bipolar disorder identified

Researchers have found two new risk loci for bipolar disorder in a genome-wide association study of 2.3 million single-nucleotide polymorphisms.

19 Mar 2014

Study provides better understanding of why chromosome errors are high in women's eggs

A new study from the University of Southampton has provided scientists with a better understanding of why chromosome errors are high in women's eggs.

19 Mar 2014

Findings reveal potential drug targets for small cell lung cancer

Cancer cells undergo extensive genetic alterations as they grow and spread through the body. Some of these mutations, known as "drivers," help spur cells to grow out of control, while others ("passengers") are merely along for the ride.

17 Mar 2014

UC Davis MIND Institute named Intellectual and Developmental Disabilities Research Center

The UC Davis MIND Institute has been named an Intellectual and Developmental Disabilities Research Center, through a prestigious grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health - a distinction held by only a handful of neurodevelopmental centers nationwide committed to the diagnosis, prevention, treatment and amelioration of developmental disorders such as autism, fragile X syndrome and Down syndrome.

14 Mar 2014

Study: Musical aptitude is affected by a combination of genes involved in auditory pathway

Multiple regions in the human genome are reported to be linked to musical aptitude, according to a study published this week in Molecular Psychiatry.

13 Mar 2014