Is there any reason to repeat a JAK2 V617F test?
A doctor may repeat this test if it was negative and she feels that the mutation may have been missed. One reason it might be negative is that the proportion of your cells that have the JAK2 V617F mutation may be low. Currently, the test is not nationally standardized, so the sensitivity of the test may vary somewhat from laboratory to laboratory. A second test done at a later time and/or sent to a different laboratory may detect the JAK2 V617F mutation if it is present. Also, some doctors may order a quantitative test periodically to monitor the change in the number of cells with the JAK2 V617F mutation over time. Results from repeated quantitative tests may be useful in monitoring the effectiveness of treatment if ongoing research shows that the JAK2 gene is an appropriate target for MPD therapies.
