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Bloom's Syndrome

Last updated: 2003-09-11

Since this syndrome was first described by New York dermatologist David Bloom in 1954, over 170 individuals have been recognized as being affected.

Bloom’s syndrome is inherited as an autosomal recessive disease. Once a couple has an affected child, there is a 1 in 4 (25%) chance for affected offspring in each future pregnancy. The gene mutation is very rare in most populations, but is more frequent among Ashkenazi Jews, where the carrier rate may be greater than 1 in 110 (approximately 1%). Carriers of Bloom’s syndrome do not manifest symptoms of the disease.

Affected individuals, who have inherited two copies of the Bloom’s syndrome gene mutation, typically have the following features: (a) unusually small size at birth but otherwise a normal degree of maturation; (b) shortness of stature after birth, only rarely reaching 5 feet; (c) redness of the skin of the face, mainly the bridge of the nose and the adjoining upper cheek areas, the lower eyelids, and the lower lip; and (d) increased numbers of respiratory tract and ear infections, some of which are life-threatening. The skin problem, which is aggravated by sun exposure, varies in severity. It may be quite disfiguring in some affected persons but mild or even absent in others, however it generally improves with age. Intelligence is usually normal, although mild deficiency has occurred in a few affected persons. Diabetes occurs in approximately 10% of individuals with Bloom’s syndrome. Infertility is the rule in men with Bloom’s syndrome, and fertility appears to be reduced in women. The risk of cancer is much greater than normal throughout life, of the variety of sites and types that affect the general population.

There is no treatment for the underlying cause of Bloom’s syndrome, and therefore medical intervention is primarily preventative. Adults with Bloom’s syndrome should be more attentive than others in their surveillance for cancer, maintaining close contact with a physician knowledgeable about the syndrome, and paying particular attention to symptoms that could be early evidence of a treatable precancerous condition. Respiratory infections require prompt antibiotic treatment. Although growth hormone therapy has been attempted to increase height in children with Bloom’s syndrome, it does not appear to be effective. In addition, there is some concern that the use of growth hormone may increase the risk for later malignancies.

The diagnosis of Bloom’s syndrome can be confirmed or ruled out by a laboratory test known as a chromosome study, as blood and skin cells show a characteristic pattern of chromosome breakage and rearrangement. Recently, the gene for Bloom’s syndrome was isolated. The gene is located on chromosome 15, and one particular mutation in the gene has been identified as the cause of Bloom’s syndrome in the vast majority of Ashkenazi Jews. Because of these recent findings, both carrier testing and prenatal diagnosis for Bloom’s syndrome are now available.