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.

Specific gene found that protects some people with diabetes from severe kidney failure

A research team at Wake Forest University Baptist Medical Center and the University of Heidelberg has proven that a gene protects some people with diabetes from developing severe kidney failure or "end-stage renal disease."

9 Jan 2007

Men who father only daughters have a higher risk of prostate cancer

In a new and unique study to determine if genes on the Y chromosome are involved in prostate cancer, researchers at Columbia University's Mailman School of Public Health in conjunction with Hebrew University of Jerusalem found that men who had only daughters had a higher risk of prostate cancer than men who had at least one son, thus signifying a possible defect on the father's Y chromosome.

3 Jan 2007

Scientists discover function for antisense RNA

Researchers have found that a class of RNA molecules, previously thought to have no function, may in fact protect sex cells from self-destructing. These findings will be published in the November 17 issue of the journal Cell.

20 Nov 2006

Scientists identify gene called HTRA1 that contributes to a major risk of Age Related Macular Degeneration

Researchers at the John A. Moran Eye Center at the University of Utah have identified a gene called HTRA1 that contributes to a major risk of Age Related Macular Degeneration (AMD), the most common cause of irreversible vision loss in the developed world.

20 Oct 2006

SUMO1 gene implicated in cleft lip and palate defects

Researchers supported by the National Institutes of Health report in the current issue of the journal Science that a much-studied gene called SUMO1, when under expressed, can cause cleft lip and palate, one of the world's most common birth defects.

21 Sep 2006

HIV needs human protein - potential therapy target

Mayo Clinic virologists have discovered that a specific human protein is essential for HIV to integrate into the human genome.

7 Sep 2006

Researchers identify genetic risk for type 1 diabetes

A discovery at the Barbara Davis Center for Childhood Diabetes has identified a genetic risk for type 1 diabetes three to four times higher than previously thought possible.

4 Sep 2006

Variation in 3 genes influences risk of age-related macular degeneration

Researchers in Boston have discovered a new common, noncoding variant in the Complement Factor H (CFH) gene that is associated with age-related macular degeneration (AMD), the leading cause of irreversible visual impairment and blindness among persons aged 60 and older.

30 Aug 2006

New novel protein-genome interaction mapping technology

Fred Hutchinson Cancer Research Center, The Netherlands Cancer Institute (NKI) and Cancer Research Technology Limited (CRT) today have released details of the development and commercialisation of a powerful protein-genome interaction mapping technology termed 'DamID.'

14 Aug 2006

Rett syndrome can also strike males

The common thinking in the past had been that Rett syndrome only affects girls.

8 Aug 2006

Gene family expansion can begin even before a gene is duplicated

Theoretical biologist Stephen Proulx studies gene families to explore how genomes become diverse and evolve.

6 Aug 2006

DNA of human embryonic stem cells is chemically modified in a characteristic, predictable pattern

Embryonic stem cells are derived from embryos that are undergoing a period of intense cellular activity, including the chemical addition of methyl groups to specific DNA sequences in a process known as DNA methylation.

6 Aug 2006

Genomic expansion and diversification in a African sleeping sickness parasite allow it to evade host detection

A team of scientists headed by Dr. Sara Melville at the University of Cambridge has shown that the parasite known to cause African sleeping sickness has evolved an unusual chromosomal structure as a result of environmental adaptation.

3 Aug 2006

Different genes may be responsible for causing autism in boys and girls

In the on-going search to find the cause of Autistic Spectrum Disorders, the latest research says different genes may be responsible for causing autism in boys than in girls, and the discovery may help explain why the condition is more common in boys.

3 Aug 2006