Image caption Chromosomes contain genetic information - too many or too few could lead to cancer.

A gene has been linked to at least three cancers in different tissues in the body, US researchers say.

Their findings, reported in the journal Science, showed a fifth of melanomas (skin cancer), Ewing's sarcomas (bone) and glioblastomas (brain) had a defective copy of the gene STAG2.

It controls the way genetic material is divided between cells.

A cancer charity said the study provided researchers with new ways of tackling the disease.

Human genetic information is bound up in 23 pairs of chromosomes. When a cell divides in two, there should be 23 pairs in each of the two cells produced.

Mutations in STAG2 appear to be a first step in the transformation of a normal cell into a cancer cell Professor Todd Waldman, Georgetown University School of Medicine

However, this does not always happen. Too many or too few chromosomes - known as aneuploidy - is common in cancer.

Chromosomes to cancer

Researchers at the Georgetown University School of Medicine, Washington, have found a gene which controls that separation of genetic material.

Defective copies of STAG2 were found in 21% of Ewing's sarcoma tumours, 19% of glioblastoma and 19% of melanoma.

Professor Todd Waldman said: "In the cancers we studied, mutations in STAG2 appear to be a first step in the transformation of a normal cell into a cancer cell.

"We are now looking at whether STAG2 might be mutated in breast, colon, lung, and other common human cancers."

Researchers believe that if they can find a drug which targets cells with defective STAG2 they will be able to stop some cancers forming.

A separate study, also published in Science, looked at the affect of aneuploidy in yeast.

Researchers at the Massachusetts Institute of Technology created 13 strains of yeast with an extra chromosome. In all cases, the yeast's genetic code become less stable and more susceptible to mutation.

The study's authors suggest the "instability could facilitate the development of genetic alternations that drive malignant growth in cancer."

Dr Julie Sharp, senior science information manager at Cancer Research UK, said: "Scientists have known for more than 100 years that having too many or too few chromosomes is linked to cancer and these results suggest that this is not just a characteristic but a cause of the disease.

"Their discovery sheds light on how chromosome numbers can be altered when cells divide and presents researchers with new ways to tackle cancer by designing drugs to upset this chain of events."