What Is Bloom Syndrome?

Bloom syndrome is an inherited disease that causes a person's chromosomes to break and rearrange frequently. Bloom syndrome is caused by mutations in the BLM gene. The chromosome instability seen in patients with Bloom syndrome causes high rates of cancer beginning in childhood or early adulthood. People with Bloom syndrome are usually smaller in stature than their peers and have a high-pitched voice. They have distinct facial features including a long, narrow face, small lower jaw, prominent nose and ears, and red lesions on the cheeks and the bridge of the nose (often described as “butterfly-shaped” lesions) which appear and worsen with sun exposure. Most people with Bloom syndrome have a normal intellectual ability, however, some will have intellectual and developmental disabilities. They may also have diabetes, chronic lung problems, and suppressed immune systems. They tend to have high rates of pneumonia and ear infections. Men with Bloom syndrome are usually infertile. Women with Bloom syndrome are fertile but often experience early menopause.

How Common Is Bloom Syndrome?

The incidence of Bloom syndrome is unknown, and fewer than 300 affected individuals have been reported. Approximately one-third of people with the disease are of Ashkenazi Jewish descent, making it more common in this population than in others. Roughly 1 in 48,000 Ashkenazi Jews is affected by the disease.

How Is Bloom Syndrome Treated?

There is no cure for Bloom syndrome. Children with Bloom syndrome need nutritional monitoring to ensure maximum growth. People with the disease are advised to stay out of the sun and wear sunscreen to prevent skin lesions, particularly during childhood. They should also make an effort to avoid infection of all kinds. In school, they may require special education classes due to learning difficulties.

People with Bloom syndrome are prone to cancer, so they should be screened regularly starting in childhood and with increasing vigilance into adulthood. Because they are particularly sensitive to radiation and DNA-damaging chemicals, standard cancer treatments often need to be modified. If diabetes is present, this condition is typically treated with diet, blood-sugar monitoring, and insulin supplements.

What Is the Prognosis for a Person with Bloom Syndrome?

Despite dealing with numerous medical problems, people with Bloom syndrome can lead productive lives. They are most often of normal or near-normal intelligence. Typically, people with Bloom syndrome lead shortened lives, although lifespan can vary greatly from person to person. The cause of death is usually cancer, which can occur in childhood, but more commonly appears in the late teens or early to mid-twenties. Early detection of cancer and appropriate treatment can help extend the lifespan of these individuals.

Other names for
Bloom syndrome

  • Bloom's syndrome
  • Bloom-Torre-Machacek syndrome
  • Congenital telangiectatic erythema


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  • German et al., 2007, Hum Mutat, 28(8):743-53, PMID: 17407155
  • OMIM: Online Mendelian Inheritance in Man, OMIM [210900], 2016, http://www.omim.org/210900
  • Sanz et al., 2013, http://www.ncbi.nlm.nih.gov/books/NBK1398/