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.

Resistance to CD19 CAR T-cell therapy can be caused by CD19 splicing alterations

Resistance to CD19 CAR T-cell therapy, a type of immunotherapy that yields long-lasting remissions in many patients with B-cell leukemia, can be caused by CD19 splicing alterations, leading to loss of certain parts of the CD19 protein that are recognized by the CAR T cells.

31 Oct 2015

Nuclear membrane fixes potentially fatal breaks in DNA strands

Scientists have found a new function of the nuclear membrane, the envelope that encases and protects DNA in the nucleus of a cell - it fixes potentially fatal breaks in DNA strands.

31 Oct 2015

Researchers develop new growth charts for U.S. children with Down syndrome

Pediatric researchers have developed the first set of growth charts for U.S. children with Down syndrome since 1988. These new charts provide an important tool for pediatricians to evaluate growth milestones for children and adolescents with this condition. With these new charts, pediatricians will be able to compare each patient's growth patterns with peers of the same age and sex who have Down syndrome.

28 Oct 2015

Study uncovers new genetic variants linked to increased risk of testicular cancer

A new study of more than 25,000 men has uncovered four new genetic variants associated with increased risk of testicular cancer.

27 Oct 2015

DNA study reveals basic principle of gene regulation

A study of where and how an enzyme cuts DNA may have inadvertently revealed a basic principle of gene regulation, say researchers in Boston Children's Hospital's Program in Cellular and Molecular Medicine (PCMM).

23 Oct 2015

Active nuclear deformations contribute to formation of intra-nuclear chromosome architectures

There are two types of chromatin, euchromatin and heterochromatin, that vary with the stages of the cell cycle. In particular, euchromatin with rich active genes localizes to the interior of the nucleus during interphase; heterochromatin usually localizes to the periphery of the nucleus.

20 Oct 2015

New genetic discovery could lead to better treatment for X-linked diseases

Think back to middle school biology class, when you learned that boys have an X and a Y chromosome inside each cell, and girls have two X's.

20 Oct 2015

New UCL study highlights genes associated with schizophrenia and obesity

Genes involved in schizophrenia and obesity have been highlighted in a new UCL study, which could lead to a better understanding of the DNA variants which affect risk of these conditions and aid the development of improved strategies for prevention and treatment.

18 Oct 2015

Only few doctors refer children with developmental delays to genetics specialists, say researchers

A nine-month-old boy isn't rolling over, reaching for objects or babbling as he should be. One step his doctor won't likely take right away: have him evaluated by a genetics specialist.

15 Oct 2015

Penn researchers show that canine X-linked retinitis pigmentosa can be cured over the long term

Three years ago, a team from the University of Pennsylvania announced that they had cured X-linked retinitis pigmentosa, a blinding retinal disease, in dogs. Now they've shown that they can cure the canine disease over the long term, even when the treatment is given after half or more of the affected photoreceptor cells have been destroyed.

13 Oct 2015

YK-4-279 compound works against some forms of leukemia: Study

A compound discovered and developed by a team of Georgetown Lombardi Comprehensive Cancer Center researchers that halts cancer in animals with Ewing sarcoma and prostate cancer appears to work against some forms of leukemia, too.

12 Oct 2015

Proposed thin-plate model sheds light on structural basis of chromosomal aberrations in cancer cells

During cell division, each metaphase chromosome contains a single enormously long DNA molecule that is associated with histone proteins and forms a long chromatin filament with many nucleosomes.

9 Oct 2015

SMC5/6 protein complex plays vital role in cancer suppression and premature ageing

A study conducted by the Spanish National Cancer Research Centre´s Genomic Instability Group, led by Óscar Fernández-Capetillo, describes for the first time in mammals, the role played by the SMC5/6 protein complex in cancer suppression and premature ageing. Mutations in these complexes, which were sensitive to chemotherapeutic agents, had been previously described in yeast cells, but their exact relationship with cancer or other diseases in mammals was unknown.

8 Oct 2015

Chromosome 3q26.2 rearrangements linked to poor CML prognosis

Rearrangements of chromosome 3q26.2 have a significant negative impact on patients with chronic myeloid leukaemia, suggests research published in Blood.

1 Oct 2015

Intratumoral morphological diversity of breast cancer not related to chromosome aberrations

Intratumor morphological heterogeneity (diversity) of breast cancer is not related to chromosome aberrations. This conclusion was made based on the study of one case with aggressive variant of breast cancer - invasive micropapillary carcinoma by researchers from Tomsk State University, Tomsk Cancer Research Institute, and Institute of Medical Genetics.

30 Sep 2015

UK Biobank genetic study shows link between lung disease and smoking behaviour

New research published in The Lancet Respiratory Medicine and presented at this year's European Respiratory Society meeting in Amsterdam presents the first analyses of genetic data from the UK Biobank that reveal new associations with lung disease and smoking behaviour.

28 Sep 2015

Researchers find mutated gene responsible for cardiac angiosarcoma in two brothers

A few years ago, Javier Benítez, director of the Human Genetics Group at the CNIO, received a call from Pablo García Pavía, from the Cardiology Unit of the Puerta de Hierro University Hospital. This cardiologist was treating two brothers with a rare form of cancer, cardiac angiosarcoma (CAS).

26 Sep 2015

Amgen gets positive CHMP opinions for Kyprolis (carfilzomib) and BLINCYTO (blinatumomab)

"We are pleased to receive positive CHMP opinions for Kyprolis and BLINCYTO as this is an important step in providing new treatment options for patients in Europe with rare forms of cancer," said Sean E. Harper, M.D., executive vice president of Research and Development at Amgen.

25 Sep 2015

Protein-coding gene identified as tumor suppressor for acute myeloid leukemia

A protein-coding gene called hnRNP K has been identified as a tumor suppressor for acute myeloid leukemia (AML), a finding that could be important for investigating how best to target treatment of a blood cancer striking mostly older individuals.

24 Sep 2015

Study uses genome- and epigenome-editing tools to determine disease-causing variants

A paper receiving advance online release in Nature Medicine describes a strategy for meeting one of today's most significant challenges in genomic medicine - determining whether a specific DNA variant in the non-protein-coding genome is the actual disease-causing variant of an associated disease risk.