Bloom Syndrome

Also known as: Congenital telangiectactic erythema

Bloom syndrome (BS) is a rare autosomal recessive chromosomal instability disorder characterised by short stature; photosensitivity; facial telangiectasia; immune deficiency; and a markedly increased susceptibility to cancer of any organ, but especially to leukaemia and lymphoma.

BS is sometimes classified as a chromosomal breakage syndrome (associated with a high frequency of chromosomal breaks and rearrangements).


Physical features of Bloom syndrome (BS) may include:

  • Pre- and postnatal growth retardation
  • Dolichocephaly
  • Narrow facies with nasal prominence and malar and mandibular hypoplasia
  • Facial sun-sensitive telangiectatic erythema in the butterfly area
  • Café-au-lait spots
  • High pitched voice
  • Variable degree of diarrhoea and vomiting during infancy


  • Patients have a 150- to 300-times increased risk of malignancy compared with the general population.
  • Acute leukaemias, lymphomas and rare tumours predominate in the first two decades of life.
  • Carcinomas occur in the second decade.


  • Patients have decreased immunoglobulin A and immunoglobulin M which manifests as recurrent respiratory tract infections complicated by otitis media and pneumonia.


  • About 10% of patients develop diabetes.


  • Affected males are usually unable to produce sperm.
  • Affected females may experience premature menopause.

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  • BS is caused by mutations in the BLM gene at 15q26.1
  • This gene encodes a RecQ helicase called the Bloom syndrome protein that helps maintain genomic stability during DNA recombination, repair and replication.
  • A significant increase in gene cluster instability and sister chromatid exchange is seen during mitotic recombination in patients with BS, which is assumed to be responsible for the phenotype and the cancer predisposition.

Gene Specific:

  • Clinical diagnosis is confirmed cytogenetically by demonstrating characteristic chromosome instability.
  • A 10-fold increase in the rate of sister chromatid exchanges is seen in Bloom Syndrome cells compared to normal cells.

Management is symptomatic and supportive, and includes:

  • Avoiding contact with direct sunlight
  • Aggressive treatment of infections
  • Avoiding X-rays and other environmental exposure to substances that cause DNA damage
  • Careful monitoring to ensure early detection of cancer (including pro-actively):
    • Annual blood count checks
    • Early inclusion for bowel cancer screening – carried out annually
    • Early inclusion into a breast cancer screening programme.
  • If any signs or suggestions of early malignancies are found, it may be appropriate to make a referral for cytogenetic testing.

Family members should be offered genetic counselling and testing. Carrier testing and pre-natal testing is available for this condition.

  • Increased risk of premature death in the second or third decade occurs secondary to malignancies.
  • Various types of leukaemia develop at a mean age of 22 years.
  • Patients who survive beyond 22 years of age tend to develop solid tumours at an average age of 35 years.
  • For children exhibiting features of Bloom Syndrome (BS), suggested initial referral would be to a paediatrician. For Jewish patients, it is important to note the child’s ancestry and higher prevalence of BS in the Jewish population.
  • For patients that have received a positive BS diagnosis:
    • On-going management is usually under the joint care of haematologists and paediatricians plus other appropriate specialists according to how the condition presents in each affected patient.
    • Families would benefit from referral to a clinical genetics department to explore carrier status in other family members as appropriate.
  • Transition from paediatric to adult management should go through an appropriate adolescent unit where possible.

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

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.

Contact A Family (UK-Based)

This charity supports families with disabled children across the UK whatever their condition or disability. They provide information, advice and support and put families in touch with others affected by similar conditions so they can support each other.


OMIM: #210900

Written by: Dr Jacky Megitt, Jnetics researcher.
Approved by: Professor Finbarr Cotter, Consultant Haematologist and Clinical Director of Pathology, Barts Health.
Last review: 24.05.2016