Bloom syndrome is a rare genetic disorder characterized by unusually small size, sensitivity to sunlight, immune-system deficiencies, and an extraordinarily high risk for developing cancer—of any type—beginning early in life. Other clinical features include chronic respiratory illness, recurrent ear infections, and diabetes. Males are infertile; females enter menopause prematurely. There are fewer than 200 known surviving cases of Bloom syndrome worldwide. Lifespan is limited; the average age of death is 27 years. The most common cause of death is from cancer.
Cancer is a disease of abnormal and unregulated proliferation of cells in the body. Most cancers are initiated as a result of a genetic mutation in the DNA and subsequently evolve through the accumulation of additional mutations into more advanced, and potentially lethal, states. In Bloom syndrome, the rate of mutation is increased manyfold for both tumor-initiating and tumor-advancing mutations. The consequence of this hypermutability in Bloom syndrome is a susceptibility to cancer development unlike any other human condition.
Persons with Bloom syndrome are predisposed to cancer in three exceptional ways:
These three features of the cancer predisposition in Bloom syndrome make it a model for the study of cancer generally. From this model, we can learn how cancer develops in other people. And, if we can figure out how to treat cancer in persons with Bloom syndrome, we learn at the same time how it can be treated in others.
There are some excellent reviews of Bloom syndrome and cancer, including an update from the Bloom Syndrome Registry of the cancers that have occurred in the 265+ persons the Registry has followed since 1954. The Registry also presents similar information on its website. To learn more about Bloom syndrome and cancer or Bloom syndrome, in general, please visit the website of the international Bloom Syndrome Association.