Nijmegen Breakage Syndrome

Researchers at the UW Medical School have found that mutations in a gene they've been studying for several years can cause ataxia-telangiectasia (A-T). The affected gene appears to play a crucial role in controlling the way cells respond to DNA damage that can lead to cancer.

The report, issued with Malcolm Taylor, a researcher from the United Kingdom, appears in the Dec. 10 issue of Cell.

A-T is a genetic disorder that produces progressive nerve and muscle loss. People with A-T are extremely susceptible to cancer. They can become severely ill if they undergo radiation therapy and some may even be harmed by exposure to low levels of radiation associated with mammography.

On the cellular level, genetic defects related to A-T produce DNA instability and damage. DNA repair mechanisms in A-T patients don't work properly, which can throw cells into serious disarray ending in cancer.

Scientists previously had identified mutations in a single gene, called ATM, as the cause of A-T, but the UW team, led by associate professor of genetics John Petrini, now reports that mutations in a closely linked neighboring gene, called Mre11, can also independently produce A-T.

Petrini's team was the first to identify and describe the Mre11 complex, a protein cluster responsible for detecting DNA damage within cells and thereby alerting them that damage is present.

"We can now definitively say that cooperation between Mre11 and ATM comprises a critical component of the regulatory network that cells activate in response to DNA damage," Petrini said. "Since mutations in this complex affect normal development as well as the ability of cells to respond to DNA damage, we infer that this network is also important for normal growth control and cancer prevention."

The UW team reported last year that mutations in a different member of the Mre11 complex, a gene called Nbs1, causes the genetic disease Nijmegen Breakage Syndrome, which closely resembles A-T.