JAK2 Mutation

Department of Haematology

Notes

• If a patient has a persistent thrombocytosis of >450 for more than 3 months with no evidence of iron deficiency or a reactive process (and is not post splenectomy)
• OR they have a significant polycythaemia with no underlying secondary cause, check a JAK2 mutation.
• Please send a 4ml in EDTA specimen and mark your request clearly as whether it is for a thrombocytosis or polycythaemia.
• Do not send this test on a Friday, as it is a genetic test and cannot be processed over a weekend.
• See G-Care for further guidance on causes of secondary thrombocytosis or polycythaemia.

JAK2 Mutation Comprises of the Following Tests

For polycythaemia;

• JAK2 p.(Val617Phe) analysis.

For thrombocytosis;

• JAK2 p.(Val617Phe) analysis, then if negative, reflex to Core MPN Panel. (CALR, JAK2 including Exon 12 and MPL).

Sample Requirements

4ml EDTA sample

Sample Storage and Retention

• Pre analysis storage: do not store, send to laboratory within 4 hours.
• Sample retention by lab: EDTA samples are retained for a minimum of 48 hours at 2-8°C.
• Transport of samples may affect sample viability, please try to avoid sending samples for genetic testing on a Friday, as there is no weekend service at North Bristol Trust.
• This test can be added on to a previous request as long as there is sufficient sample remaining and the sample is less than 24 hours old.

Turnaround Times

3 weeks

Reference Ranges

Positive or negative interpretation provided by Bristol Haemato-Oncology Diagnostic Service.

Information for Laboratory Staff Only

When the sample comes in, on the BHODs form, select the following;

• If marked thrombocytosis - select JAK2 and CALR / MPL.
• If marked polycythaemia - just select the JAK2.