Gene discovery sheds light on causes of rare disease, cancer

National Institute on Aging (NIA) researchers have discovered a new gene, FANCM, which sheds light on an important pathway involved in the repair of damaged DNA. Specifically, mutation in this gene is responsible for one of the forms of Fanconi anemia (FA), a rare genetic disorder that primarily affects children. Like many rare, inherited diseases, understanding this gene's role in the development of FA provides insights into other medical problems -- in this case, age-related conditions including ovarian and pancreatic cancers, as well as leukemia, the researchers said. Discovery of this gene and its protein provides a potential target for the development of drugs that can prevent or alleviate FA and a variety of cancers.

The finding is scheduled for advanced online publication in Nature Genetics (http://www.nature.com/ng/) during the week of August 21, 2005.* The report also will be published in the journal's September 2005 print edition. The NIA is a component of the National Institutes of Health (NIH) at the U.S. Department of Health and Human Services.

"FA is a disease that appears to be the result of a breakdown in vital DNA repair mechanisms," said Weidong Wang, Ph.D., a senior investigator in the NIA's Laboratory of Genetics, who led the study. "Some scientists theorize that DNA damage, which gradually accumulates as we age, leads to malfunctioning genes and deteriorating tissues and organs as well as increased risk of cancer. We believe that this new gene, FANCM, may be a potent cog in the DNA repair machinery," Wang said. "It is possible that we could learn how to promote the function of DNA repair complexes and thereby prevent the age-related accumulation of DNA damage."

FANCM, like most genes, contains information for making a specific protein. The FANCM protein, part of the molecular machine called the FA core complex, is the only protein within this machine that affects DNA by enzyme activity (enzymes are proteins that encourage biochemical reactions, usually speeding them up). FANCM apparently provides an engine that moves the FA DNA repair machine along the length of DNA. It also is a key component of the complex that is switched "on" or "off" by phosphorylation, or the addition of a phosphate group to a protein, in response to DNA damage. In the future, researchers hope to use the newly-discovered activities of FANCM as targets to select drugs that enhance the FA DNA damage response for intervention in patients.

Fanconi anemia, named for Swiss pediatrician Guido Fanconi, affects about 1 in every 300,000 children. If both parents have the same mutation in the same FA gene, each of their children has a one-in-four chance of inheriting the defective gene from both parents and developing FA or certain types of cancer. The disease leads to bone marrow failure (aplastic anemia) and is associated with birth defects such as missing or extra thumbs and skeletal abnormalities of the hips, spine, or ribs. Many who have FA eventually develop acute myeloid leukemia and are prone to head and neck, gastrointestinal, and other cancers. The first symptoms, such as nose bleeds or easy bruising, usually begin before age 12. In rare instances, however, symptoms do not become apparent until adulthood. This is the third FA gene and protein combination identified in the last 3 years by Wang and his colleagues.

Source : NIH/National Institute on Aging