Canavan Disease

Bloom Syndrome

Bloom syndrome is a condition characterised by poor growth, increased skin sensitivity to sunlight, frequent infections and a predisposition to certain cancers.

If you have just received a diagnosis there is help and support available – see ‘further information and support’ below for links to valuable resources. Also, please note that not every affected person will experience all the symptoms outlined – to better understand your/your family members’ individual case, we recommend you talk to your doctor or healthcare specialist.
Bloom Syndrome is an autosomal recessive condition.


The carrier frequency in the Ashkenazi Jewish population is approximately 1 in 100.


Common signs and symptoms of Bloom syndrome include:

  • Unusually small size at birth but otherwise normal
  • Restricted growth after birth, only rarely reaching 5 feet tall
  • Increased sensitivity to sunlight, which can result in redness of the facial skin
  • Increased numbers of respiratory tract and ear infections
  • Males are typically infertile; females have reduced fertility and premature menopause
  • Diabetes is more common than in the general population (affecting approximately 10% of people with the syndrome)
  • The risk of cancer is much greater than normal relative to the general population
  • Intelligence is typically normal, though mild deficiency has been found in a few cases.


Please click on the titles to open and close the following information sections.

The syndrome is caused by changes in the BLM gene that is responsible for copying and repairing DNA in cells. The condition is considered a ‘chromosome breakage’ disease because these changes result in a high incidence of breaks in the affected individual’s chromosomes.

There is currently no cure for Bloom syndrome, but there are recommendations for managing the symptoms, e.g. people affected by the syndrome would benefit from monitoring for the signs of cancer or pre-cancerous conditions, and decreasing their exposure to sunlight and x-rays.

People with Bloom syndrome have a shortened life-span, typically as a consequence of a cancer-related illness.

The syndrome can be diagnosed clinically by a doctor familiar with the symptoms. The diagnosis can be confirmed or ruled out using genetic testing as the gene for Bloom syndrome has been identified.

Both prenatal testing and carrier testing for the condition are now possible.

For more details about testing, please refer to the testing section.

There is currently no UK-based patient group dedicated to BS, however, the international resources below provide further information and support for the condition.

The Bloom’s Syndrome Association (USA)

The BSA’s mission is to promote communication and foster advocacy among its members; to raise funds for Bloom’s syndrome research, projects, programs, and events; and to publicize the syndrome’s importance to human health, especially to worldwide cancer research.

Bloom’s Connect (USA)

An American-based website designed to connect people living with BS and answer questions that might arise about living with the condition.

Bloom’s Connect on Facebook

An international support group on Facebook for people with Bloom syndrome.

The Bloom’s Syndrome Registry (USA)

Affiliated with Cornell University, the registry collects data from international volunteers with BS in order to better characterize and understand the disorder. The site provides information about BS and contact details for anyone interested in participating or learning more.

To find out more about general resources relevant to Jewish genetic disorders, visit our resources and support section.

Written by Jnetics.
Approved by Professor Finbarr Cotter, Professor of Haematology at the Centre for Haemato-Oncology at Barts Cancer Institute, Queen Mary, University of London.
Last review: 24.11.2014