Skip to main content

This site is best viewed with a modern browser. You appear to be using an old version of Internet Explorer.

Monitoring for G(M)CSF escape mutations (R338)

Granulocyte colony stimulating factor (G-CSF or CSF3) is a hematopoietic cytokine that stimulates neutrophil production and is commonly used to treat severe congenital neutropenia (SCN) or neutropenia induced by chemotherapy.

However, continued treatment for several years is associated with an increased risk of malignant transformation to leukaemia. This is associated with somatic activating mutations in the G-CSF receptor gene, CSF3R, therefore monitoring for such mutations in patients on long-term G-CSF therapy is available.

Dominant negative mutations in the CSF3R gene are a cause of severe congenital neutropenia. Testing for this clinical indication is provided as part of the 'Cytopenia - Not Fanconi Anaemia' panel under test code R91.1.

NHSE funded test referrals should meet the relevant NHSE eligibility criteria.

Testing strategy

Patients with neutropenia on long term G-CSF therapy

R338.1 - single gene analysis for small variants in the CSF3R gene.

Target reporting times

Test target reporting time is 21 days.

For other reporting times, please see turnaround times.

Sample requirements and referral information

Clinical guidance and advice is available to referring clinicians from:

Dr NoƩmi Roy
Consultant Haematologist
John Radcliffe Hospital


Referral form is available from our website. See referral forms and specimen requirements and referring samples.

Requesting specialties

  • Haematology
  • Immunology
  • Oncology

Contact details

See contact us.

Price list for non NHSE referrals

Price list for rare disease services (pdf)

Last reviewed:02 August 2021