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.

Researchers identify chromosomal make-up of human eggs

In a groundbreaking study, Yale School of Medicine researchers and colleagues at the University of Oxford have identified the chromosomal make-up of a human egg. This discovery may soon allow them to avoid using abnormal - or aneuploid - eggs during infertility treatments, and instead to pick eggs that are healthy enough for a successful in vitro fertilization (IVF) cycle.

2 Jun 2012

Distinctive protein pathways in certain leukemia patients

Scientists at Rice University and the University of Texas MD Anderson Cancer Center have successfully profiled protein pathways found to be distinctive to leukemia patients with particular variants of the disease.

1 Jun 2012

Verinata Health to present two key studies on verifi prenatal test at ISPD conference

Verinata Health, Inc., a privately-held company dedicated to maternal and fetal health, today announced that physicians across the country are now using the verifi prenatal test.

1 Jun 2012

Gender link discovered for colorectal cancer

Researchers have identified three new colorectal cancer risk loci, including one on the X-chromosome, bringing the total number of independent loci associated with the disease to 20.

30 May 2012

JTCC to present latest findings in blood-cancer research at ASCO annual meeting

Physicians and researchers at John Theurer Cancer Center at HackensackUMC, one of the nation's top 50 cancer centers, will present the latest findings in blood-cancer research at the 2012 American Society of Clinical Oncology (ASCO) annual meeting in Chicago on June 1-5. Their involvement in these studies is part of John Theurer Cancer Center's continued focus to bolster its research program.

30 May 2012

Researchers uncover insights into rare genetic disorders

Researchers studying rare genetic disorders have uncovered insights into those diseases in biological structures that regulate chromosomes when cells divide. Focusing on the cohesin complex, a group of proteins forming a bracelet that encircles chromosome pairs, scientists have discovered mutations that disrupt cohesin, causing a recently recognized class of diseases called cohesinopathies.

30 May 2012

Naphthalene exposure may increase risk of chromosomal aberrations in children

According to a new study, children exposed to high levels of the common air pollutant naphthalene are at increased risk for chromosomal aberrations (CAs), which have been previously associated with cancer. These include chromosomal translocations, a potentially more harmful and long-lasting subtype of CAs.

30 May 2012

CDKN1C gene mutation contributes to IMAGe syndrome

A gene previously linked to too much growth in patients has now also been linked to growth restriction. Different forms of the gene can lead to very different conditions, according to research published today in the journal Nature Genetics.

28 May 2012

UCLA geneticists identify mutation responsible for IMAGe syndrome

UCLA geneticists have identified the mutation responsible for IMAGe syndrome, a rare disorder that stunts infants' growth. The twist? The mutation occurs on the same gene that causes Beckwith-Wiedemann syndrome, which makes cells grow too fast, leading to very large children.

28 May 2012

Scientists show how hemizygous deletion can contribute to cancer

Chromosomal deletions in DNA often involve just one of two gene copies inherited from either parent. But scientists haven't known how a deletion in one gene from one parent, called a "hemizygous" deletion, can contribute to cancer.

28 May 2012

X-chromosome involved in development of bowel cancer

Scientists have shown for the first time that one of the sex chromosomes is involved in the development of a cancer that can afflict both genders, according to a Cancer Research UK-funded study in Nature Genetics.

28 May 2012

Researchers identify genetic marker linked with smoking quantity in African Americans

In a step toward understanding possible genetic differences in smoking behaviors, a team of researchers co-led by SRI International has identified a genetic marker associated with smoking quantity in people of African ancestry.

23 May 2012

Prenatal Diagnosis publishes Sequenom CMM’s MaterniT21 PLUS LDT clinical study

Sequenom, Inc., a life sciences company providing innovative genetic analysis solutions, today announced that a new publication from the large Women & Infants multi-center clinical study on the Sequenom Center for Molecular Medicine's (Sequenom CMM) MaterniT21 PLUS laboratory-developed test (LDT) has been published online in the peer-reviewed journal, Prenatal Diagnosis.

19 May 2012

Researchers identify mechanism by which Zds1 protein regulates key function in mitosis

Researchers from the Bellvitge Biomedical Research Institute (IDIBELL) have identified the mechanism by which protein Zds1 regulates a key function in mitosis, the process that occurs immediately before cell division.

19 May 2012

Vejthani Hospital offers most effective procedure in gender selection

Vejthani Hospital Bangkok recommends a gender selection procedure for a couple who desire to choose a child's gender at Vejthani ART Center.

16 May 2012

Genetic test can accurately predict spread of eye cancer

Researchers at Washington University School of Medicine in St. Louis have developed a genetic test that can accurately predict whether the most common form of eye cancer will spread to other parts of the body, particularly the liver.

15 May 2012

Study: Y and W chromosomes are very important in fertility

The study, published yesterday in the journal Proceedings of the National Academy of Sciences (PNAS), looked at how genes on sex-linked chromosomes are passed down generations and linked to fertility, using the specific example of the W chromosome in female chickens.

9 May 2012

Two studies suggest long-term value of Deplin in treating MDD

Two studies presented this week at the 164th Annual Meeting of the American Psychiatric Association suggest the long-term value of Deplin (L-methylfolate 15mg) in treating major depressive disorder (MDD) and describe subsets of patients who may benefit more robustly from this medical food.

9 May 2012

Research grants on facioscapulohumeral dystrophy prove useful as genetic basis is found

Businessman Bill Moss’s determination to fight his untreatable muscle-wasting disease may have paid off. Four years ago, Mr Moss, a former Macquarie Bank Executive Director, established a charitable research foundation, FSHD Global, which partly funded the Italian researchers who made the breakthrough.

8 May 2012

Presence of fetal cells is a double-edged sword for women

For the first time, scientists have found what could be a causative link between the concentration of circulating Y-chromosome fetal cells in women who gave birth to children of either sex and their risk of later developing breast cancer and colon cancer.

4 May 2012