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.

PHF21A gene plays a big role in Potocki-Shaffer syndrome

A gene whose mutation results in malformed faces and skulls as well as mental retardation has been found by scientists.

6 Jul 2012

Researchers use maternal blood sample to sequence genome of an unborn baby

Researchers at the Stanford University School of Medicine have for the first time sequenced the genome of an unborn baby using only a blood sample from the mother.

5 Jul 2012

Researchers use mouse model of autism to treat CTD

Using a mouse model of autism, researchers at the University of Cincinnati (UC) and Cincinnati Children's Hospital Medical Center have successfully treated an autism spectrum disorder characterized by severe cognitive impairment.

3 Jul 2012

Osteoarthritis susceptibility: eight potential genes discovered

The largest genome-wide association study (GWAS) of osteoarthritis to date, published Online First in The Lancet, has uncovered eight new genetic variants or loci that appear to increase susceptibility to the most common form of arthritis, which affects about 40% of the world population older than 70 years. These findings bring the total number of osteoarthritis susceptibility genes isolated in European populations to 11.

3 Jul 2012

Researchers show how aggressive form of multiple myeloma resists chemotherapy

Researchers at Washington University School of Medicine in St. Louis have shown how an aggressive form of multiple myeloma resists chemotherapy.

3 Jul 2012

Genetic mutation that creates Ewing's sarcoma leads to high levels of protein EYA3

Ewing's sarcoma is a bone cancer commonly diagnosed in about 250 U.S. teenagers per year. If early chemotherapy is effective, improvement can be durable. But for children and teens who respond poorly to a first attempt at chemotherapy or if the disease spreads, long-term survival can be less than 10 percent.

30 Jun 2012

Study suggests adverse role for BclI polymorphism in obesity and insulin resistance

A large study in people at risk of diabetes has found a direct association between the presence of a small genetic alteration in a hormone receptor and increased body fat and insulin resistance. The results, to be presented Tuesday at The Endocrine Society's 94th Annual Meeting in Houston, suggest an adverse role for a previously described genetic variant, the BclI polymorphism.

28 Jun 2012

Study reveals decline in number of babies born with birth defects across Europe

The number of babies born with birth defects (major congenital anomalies) across Europe has fallen over the decade (2000-2009), University of Ulster research has revealed.

23 Jun 2012

Oxytocin hormone plays an important role in Williams syndrome

The hormone oxytocin - often referred to as the "trust" hormone or "love hormone" for its role in stimulating emotional responses - plays an important role in Williams syndrome (WS), according to a study published June 12, 2012, in PLoS One.

23 Jun 2012

Scientists identify cause of double-cortex syndrome

Researchers at McGill University have discovered the cause of an inherited form of epilepsy. The disease, known as double-cortex syndrome, primarily affects females and arises from mutations on a gene located on the X chromosome. Drs. Susanne Bechstedt and Gary Brouhard of the Department of Biology have used a highly advanced microscope to discover how these mutations cause a malformation of the human brain.

22 Jun 2012

Six novel genetic associations for early onset male pattern baldness

Using data from its unique online research platform, 23andMe, a leading personal genetics company, has contributed to the finding of six novel genetic associations for early onset male pattern baldness (androgenetic alopecia) in a genome-wide association study now published online in the journal PLoS Genetics.

20 Jun 2012

Zebrafish provides insight into human melanoma

A transparent member of the minnow family is providing researchers at Weill Cornell Medical College in New York City with insight into human melanoma - a form of skin cancer - that may lead to new or repurposed drug treatments, for skin and other cancers.

19 Jun 2012

Updated data from ARIAD’s ponatinib pivotal trial on CML or Ph+ ALL

ARIAD Pharmaceuticals, Inc. today announced updated clinical data from the pivotal PACE trial of its investigational pan-BCR-ABL inhibitor, ponatinib, in patients with chronic myeloid leukaemia (CML) or Philadelphia-positive acute lymphoblastic leukaemia (Ph+ ALL), who are resistant or intolerant to dasatinib or nilotinib or who have the T315I mutation.

18 Jun 2012

Otsuka, Bristol-Myers Squibb announce six-year data from SPRYCEL Phase 3 trial on CP-CML

Bristol-Myers Squibb Company and Otsuka Pharmaceutical Europe Ltd., today announced six-year follow-up results from a Phase 3 randomised, open-label, dose-optimisation study of SPRYCEL (dasatinib) in Philadelphia chromosome-positive (Ph+) chronic-phase chronic myeloid leukaemia (CP-CML) adult patients resistant or intolerant to Glivec (imatinib).

16 Jun 2012

First U.S. population prevalence study of mutations in the gene that causes fragile X

The first U.S. population prevalence study of mutations in the gene that causes fragile X syndrome, the most common inherited form of intellectual disability, suggests the mutation in the gene - and its associated health risks - may be more common than previously believed.

15 Jun 2012

Study finds gender pay disparity among physicians

Male doctors make more money than their female counterparts, even when factoring in medical specialty, title, work hours, productivity and a host of other factors, according to a comprehensive new analysis from researchers at the University of Michigan Health System and Duke University.

13 Jun 2012

Genes ‘choose only good eggs’ for IVF

Researchers have identified a technique that could help them “pick the right egg” for in vitro fertilization treatment.

8 Jun 2012

dSarm/Sarm1 gene promotes axon destruction after injury

Degeneration of the axon and synapse, the slender projection through which neurons transmit electrical impulses to neighboring cells, is a hallmark of some of the most crippling neurodegenerative and brain diseases such as amyotrophic lateral sclerosis (ALS), Huntington's disease and peripheral neuropathy.

8 Jun 2012

Study describes how seizures in people with AS could be linked to brain cell activity imbalance

New research by scientists at the University of North Carolina School of Medicine may have pinpointed an underlying cause of the seizures that affect 90 percent of people with Angelman syndrome (AS), a neurodevelopmental disorder.

7 Jun 2012

New region on the X chromosome plays a role in migraine

New hope has arrived for migraine sufferers following a Griffith University study with the people of Norfolk Island. Led by Professor Lyn Griffiths from the University's Griffith Health Institute, the team has identified a new region on the X chromosome as playing a role in migraine.

5 Jun 2012