Washington, Apr 23 : A new study has found that a miscue in the body’s genetic repair system may lead to the onset of Huntington’s Disease.

Huntington Disease (HD) is a genetic disorder of the central nervous system, characterised by repeated DNA segment CAG. It is a fatal condition that affects 30,000 Americans annually.

The study was conducted by a team of researchers from Mayo Clinic, National Institutes of Health (NIH) and University of Oslo, Norway, and was led by Cynthia McMurray, and NIH Director Elias Zerhouni.

Scientists studied the DNA segment in transgenic mice that carried the human Huntington’s gene and noted that repeated tracts of replacement repair segments seemed stable until the animals reached four months of age. At that point which represents middle age for a mouse, the segments were found to be expanding and continued to do so as the animal aged further.

The researchers also showed that the expansion of the tracts, an inherited characteristic, also caused toxicity in cells that cannot expand, such as nerve cells. They concluded that cell death acceleration is directly proportional to additional repeated length.

The research team further eliminated a key enzyme (OGG1), which is related to DNA repair for oxidative lesions, and found that it stopped or greatly reduced segment growth.

This, they said, may position OGG1 as a target candidate for interventional therapies to disrupt the onset of the disease.

“We showed that when single-strand breaks in DNA caused by oxidative lesions were repaired, the Huntington’s gene continued to add extra replacement segments. Over time, this expansion — especially in nerve cells — becomes toxic,” McMurray said.

Researchers for the first confirmed a connection between the DNA repair and progression of Huntington disease.

“As so often happens, basic research on a fundamental biological process — in this case, enzymes involved in DNA repair — leads to new insights about how diseases arise and new approaches for treating or preventing them,” Zerhouni said.

The findings of the research will be published in the online issue of the journal Nature. (ANI)