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.

Genetic architecture controlling growth of 'back-up' blood vessels uncovered

Researchers at the University of North Carolina at Chapel Hill School of Medicine have uncovered the genetic architecture controlling the growth of the collateral circulation - the "back-up" blood vessels that can provide oxygen to starved tissues in the event of a heart attack or stroke.

20 Aug 2010

Scientists discover genetic flaw that causes facioscapulohumeral muscular dystrophy

Nearly two decades after they identified the specific genetic flaw that causes a common type of muscular dystrophy, scientists believe they have figured out how that flaw brings about the disease. The finding by an international team of researchers settles a longstanding question about the roots of facioscapulohumeral muscular dystrophy or FSHD.

20 Aug 2010

Genome-wide study identifies key genetic variant associated with nonalcoholic fatty liver disease

Researchers at Massachusetts General Hospital found that patients with nonalcoholic fatty liver disease (NAFLD) who carry an allele of the PNPLA3 gene have an increased risk of developing advanced disease, including nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. A second study supported by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) validates these findings and further concludes that in pediatric patients, the same allele is associated with earlier disease presentation.

18 Aug 2010

Research confirms genetic link to advanced fatty liver disease

17 Aug 2010

Researchers discover genetic alterations responsible for Kabuki syndrome

Using a new, rapid and less expensive DNA sequencing strategy, scientists have discovered genetic alterations that account for most cases of Kabuki syndrome, a rare disorder that causes multiple birth defects and mental retardation. Instead of sequencing the entire human genome, the new approach sequences just the exome, the 1-2 percent of the human genome that contains protein-coding genes.

16 Aug 2010

GWA Study helps scientists identify genetic variant that increases tuberculosis susceptibility in African populations

Scientists have identified a genetic variant which increases susceptibility to tuberculosis (TB) in African populations using a technique known as a genome-wide association (GWA) study. This is the first novel disease variant to be identified using this technique in Africans and demonstrates that such studies are viable in African populations, which have a high degree of genetic diversity.

9 Aug 2010

Alnylam publishes research findings of Sort1 gene role in cardiovascular disease development

Alnylam Pharmaceuticals, Inc. a leading RNAi therapeutics company, announced today the publication of new research findings in the journal Nature describing the discovery and validation of the role of the gene Sort1 in the development of cardiovascular disease, including myocardial infarction (MI). This work was done with collaborators at University of Pennsylvania (UPenn) School of Medicine, Massachusetts General Hospital (MGH), and the Broad Institute. The collaborative effort combined genome-wide association studies (GWAS) and RNAi technology to identify and validate novel genes as targets for new therapies for heart disease.

6 Aug 2010

Scientists identify genetic variant that increases risk of schizophrenia

A group of scientists has identified a genetic variant that substantially increases the risk for developing schizophrenia in Ashkenazi Jewish and other populations. The study, published by Cell Press on August 5th in the American Journal of Human Genetics, associates a deletion on chromosome 3 with increased incidence of schizophrenia.

6 Aug 2010

Researchers identify gene associated with susceptibility to chronic pain caused by nerve injury

Researchers at the Hebrew University of Jerusalem and elsewhere have succeeded in identifying for the first time a gene associated with susceptibility to chronic pain caused by nerve injury in humans, signaling a significant step toward better understanding and treating of the condition.

6 Aug 2010

Gene associated with susceptibility to chronic pain caused by nerve injury identified

Researchers at the Hebrew University of Jerusalem and elsewhere have succeeded in identifying for the first time a gene associated with susceptibility to chronic pain caused by nerve injury in humans, signalling a significant step toward better understanding and treating of the condition.

5 Aug 2010

ARIAD reports $159.3 million second-quarter net income

ARIAD Pharmaceuticals, Inc. today reported financial results for the second quarter and six months ended June 30, 2010 and provided an update on corporate developments.

5 Aug 2010

SORT1 pathway holds promise as new target for therapeutic intervention for LDL cholesterol reduction

The true power of genomic research lies in its ability to help scientists understand biological processes, particularly those that - when altered - can lead to disease. This power is demonstrated dramatically in a pair of papers published today in the journal Nature. In the first, a global team of researchers describes 95 different variations across the genome that contribute in different degrees to alterations in blood cholesterol and triglyceride levels in multiple human populations. In the second report, close examination of just one of these common variants not only reveals the involvement of an unexpected genetic pathway in lipid metabolism but also provides a blueprint for using genomic findings to unravel biological connections between lipid levels and coronary heart disease.

5 Aug 2010

People insensitive to quinine's bitter taste may have varied absorption, metabolization capabilities: Study

Some people find quinine to be bitter while others can drink it like water. Now, scientists from the Monell Center and collaborators report that individual differences in how people experience quinine's bitterness are related to underlying differences in their genes.The findings, published online in the journal Human Molecular Genetics, demonstrate that genetic variation in regions of DNA that encode bitter taste receptors predicts a person's perception of bitterness from quinine.

3 Aug 2010

Genetics research team discovers new recurrent translocations

A genetics research team based at The Children's Hospital of Philadelphia continues to discover recurrent translocations—places in which two chromosomes exchange pieces of themselves. As many as 1 in 600 persons carry balanced chromosome translocations, which involve no loss or gain of DNA. Most such people appear healthy, but may have a child with abnormal chromosome composition and disabilities resulting from disrupted, extra or missing copies of genes.

30 Jul 2010

Bio-Path commences dosing in Liposomal Grb-2 Phase I cancer study

Bio-Path Holdings, Inc.,, a biotechnology company with drug development operations in Houston, Texas, announced today that the first patient has been dosed in a Phase I study of its cancer drug candidate, Liposomal Grb-2 (L-Grb-2 or BP-100-1.01), in patients with Acute Myeloid Leukemia (AML), Chronic Myelogenous Leukemia (CML), Acute Lymphoblastic Leukemia (ALL) or Myelodysplastic Syndrome (MDS).

30 Jul 2010

Study on link between SNP and concentrations of serum creatinine

Scientists at deCODE genetics and colleagues at Radboud University in the Netherlands today describe how the impact of a single letter variation in the sequence of the human genome conferring risk of kidney disease varies with age and with the onset of other diseases. The study provides independent confirmation of the association made in an earlier study between a version of the the SNP, located on chromosome 16p12, and risk of chronic kidney disease. It also confirmed the link between the SNP and concentrations of serum creatinine, a key indicator of kidney function.

30 Jul 2010

Scientists identify new targets to develop treatment for HD

Scientists at the Buck Institute for Age Research have discovered that a particular family of enzymes are involved in the breakdown of proteins that modify the production of toxic fragments that lead to the pathology of Huntington's disease. These enzymes, matrix metalloproteinases, provide new targets for drug therapies for the disease - targets that have already been shown to respond to cancer drugs currently in clinical development.

29 Jul 2010

Circulating aberrant cells increase as non-small cell lung cancer progresses

A novel approach detects genetically abnormal cells in the blood of non-small cell lung cancer patients that match abnormalities found in tumor cells and increase in number with the severity of the disease, a research team led by scientists at The University of Texas MD Anderson Cancer Center report in the journal Clinical Cancer Research.

23 Jul 2010

Researchers discover new gene regulation, DNA behavior of breast cancer cells

Cancer researchers have discovered a previously unknown type of gene regulation and DNA behavior in breast cancer cells that may lead to better insight about environmental exposure to estrogen-like compounds. A new study, published in the journal Genome Research by researchers at The Ohio State University Comprehensive Cancer Center-Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC-James), provides the first evidence that cells can regulate many genes at once by looping their DNA, contributing to cancer when it goes awry. In this study, the gene regulation was discovered in breast cancer cells as a response to the hormone estrogen and resulted in the silencing of 14 genes at one time.

20 Jul 2010

Researchers discover genetic explanation for non-diabetic kidney disease in African-Americans

Kidney disease is a growing public health problem, with approximately half a million individuals in the United States requiring dialysis treatments to replace the function of their failed kidneys. The problem is particularly acute among African-Americans, whose rates of kidney disease are four times higher than those of European Americans.

20 Jul 2010

Chromosome X News and Research

Further Reading

Genetic architecture controlling growth of 'back-up' blood vessels uncovered

Scientists discover genetic flaw that causes facioscapulohumeral muscular dystrophy

Genome-wide study identifies key genetic variant associated with nonalcoholic fatty liver disease

Research confirms genetic link to advanced fatty liver disease

Researchers discover genetic alterations responsible for Kabuki syndrome

GWA Study helps scientists identify genetic variant that increases tuberculosis susceptibility in African populations

Alnylam publishes research findings of Sort1 gene role in cardiovascular disease development

Scientists identify genetic variant that increases risk of schizophrenia

Researchers identify gene associated with susceptibility to chronic pain caused by nerve injury

Gene associated with susceptibility to chronic pain caused by nerve injury identified

ARIAD reports $159.3 million second-quarter net income

SORT1 pathway holds promise as new target for therapeutic intervention for LDL cholesterol reduction

People insensitive to quinine's bitter taste may have varied absorption, metabolization capabilities: Study

Genetics research team discovers new recurrent translocations

Bio-Path commences dosing in Liposomal Grb-2 Phase I cancer study

Study on link between SNP and concentrations of serum creatinine

Scientists identify new targets to develop treatment for HD

Circulating aberrant cells increase as non-small cell lung cancer progresses

Researchers discover new gene regulation, DNA behavior of breast cancer cells

Researchers discover genetic explanation for non-diabetic kidney disease in African-Americans

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