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Breast cancer gene linked to rare childhood anemia


Research into a rare childhood disorder has revealed a connection between the genes that cause it and those that cause breast cancer. A new study, published in Science, found that the breast cancer-susceptibility gene BRCA2 can cause the disease Fanconi anemia (FA), illuminating the link between breast cancer genes and six previously identified FA genes.

The study reports that both the FA genes and the two breast cancer genes BRCA1 and BRCA2 are part of the same DNA repair pathway. If mutated breast cancer genes can cause FA, it seems, then mutated FA genes could cause cancer.

‘A prime example of how research into rare conditions can lead to better diagnosis for more common diseases.’

Patients with one mutant copy of BRCA2 are known to be at risk for breast cancer; individuals with a family history of the disease are often tested for defective BRCA2 genes. This research suggests that testing for mutant FA genes would be useful as well, since they are part of the same pathway. Such testing would more effectively establish a patient's cancer susceptibility.

The researchers suspected that the two breast cancer genes and six FA genes were collectively responsible for maintaining the stability of each cell's entire genome. The six FA genes, they hypothesized, together activate BRCA1 and BRCA2, which in turn code for DNA-repair proteins. If any of the genes involved in this sequence is disturbed, damaged DNA in the cell might go unrepaired. This could eventually lead to unchecked mutations and tumors.

The study, led by Niall G. Howlett of Boston's Dana-Farber Cancer Institute, examined the breast cancer genes of FA patients whose FA genes were all normal. Using DNA analysis, Howlett and colleagues determined that both copies of these patients' BRCA2 genes were damaged. Defects in BRCA2 are evidently sufficient to cause Fanconi anemia, suggesting that the FA genes and breast cancer genes do indeed work together.

Characterized by congenital abnormalities such as skeletal defects, progressive bone marrow failure, and susceptibility to many cancers, Fanconi anemia is an extremely rare condition (about 1 per 100,000 live births). BRCA2 mutations, furthermore, cause FA in only five percent of these patients.

Research into these extremely rare cases, however, has led to critical realizations about cancer susceptibility, according to researcher Alan D. D'Andrea, also of Dana-Farber. In a press statement, D'Andrea remarked "this work is a prime example of how research into rare conditions can lead to better diagnosis and treatment for people with far more common diseases."

Diagram of the reactions of the FA and BRCA proteins in a common pathway.

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Howlett, N.G. et al. Biallelic inactivation of BRCA2 in Fanconi anemia. Science Express. Published online June 13, 2002.

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