# Bloom syndrome

Source: https://onco.cc/terms/bloom-syndrome/  
OnCo record `bloom-syndrome` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Bloom syndrome is a rare inherited condition, caused by two faulty copies of the BLM gene, that causes small stature, a sun-sensitive facial rash and a high risk of many cancers from childhood. Colonoscopy from age 10 to 12, sun protection and care at a specialist centre are recommended, and cancer treatment has to be adapted.

## Summary

Autosomal recessive, biallelic variants in the RecQ helicase gene BLM; increased sister chromatid exchange is characteristic. An Ashkenazi Jewish founder variant is known. Cumulative incidence of any cancer is 52% by 30 and 82.5% by 40; haematological cancers (ALL, AML, lymphoma) are about a third, gastrointestinal tumours second, and oropharyngeal, breast, skin cancer and Wilms tumour also occur.

AACR 2024: at least annual clinical assessment and education about leukaemia and Wilms tumour symptoms; routine whole-body MRI and Wilms tumour ultrasound are no longer recommended; colonoscopy from 10 to 12, because some develop polyps before cancer and the youngest colorectal cancer was at 16; dose-reduced, alkylator-sparing chemotherapy; avoiding radiation; sun protection and an annual skin check.

## Fields

- Kind: Term
- Last checked: 2026-11-04
- Also known as: BLM syndrome
- Tags: gap-fill; hereditary

## Notes

- NHS England genomic test directory: R229, confirmed Fanconi anaemia or Bloom syndrome. Orphanet ORPHA:125.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Bloom_syndrome
- Nakano, Clin Cancer Res 2024: cancer screening in children with genomic instability disorders (AACR update): https://doi.org/10.1158/1078-0432.ccr-24-1098
- Orphanet ORPHA:125: https://www.orpha.net/en/disease/detail/125
- NHS England National Genomic Test Directory, rare and inherited disease, version 9 (spreadsheet): https://www.england.nhs.uk/wp-content/uploads/2018/08/rare-and-inherited-disease-national-genomics-test-directory-v9.xlsx

## Connected records

- cancers: [Acute lymphoblastic leukaemia](https://onco.cc/cancers/all-leukemia/), [Acute myeloid leukaemia](https://onco.cc/cancers/aml/), [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- technologies: [Germline (hereditary) testing](https://onco.cc/technologies/germline-testing/)
- targets: [BLM](https://onco.cc/targets/blm/)
- terms: [Colonoscopy](https://onco.cc/terms/colonoscopy/), [Hereditary cancer syndromes](https://onco.cc/terms/hereditary-cancer-syndromes/), [Inherited susceptibility to acute lymphoblastic leukaemia (PAX5, ETV6, IKZF1)](https://onco.cc/terms/germline-all-predisposition/)
- drugs: [Helix Hereditary Comprehensive Cancer Panel](https://onco.cc/drugs/helix-hereditary-cancer/), [Invitae Multi-Cancer Panel](https://onco.cc/drugs/invitae-multi-cancer-panel/)

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