FIP1L1-PDGFRA is an abnormal fusion gene sequence that causes excessive growth of eosinophils, a type of white blood cell. It is a rare cause of hypereosinophilia (HE) and hypereosinophilic syndrome (HES). This test detects the FIP1L1-PDGFRA gene sequence.

The result of the test may be reported as “positive” (the gene sequence is present) or as “negative” (the gene sequence is not present).

If a person has abnormally high numbers of eosinophils and tests positive for the FIP1L1-PDGFRA fusion gene, then the fusion gene is confirmed as the underlying cause of that person’s hypereosinophilia (HE) or hypereosinophilic syndrome (HES).

If a person tests negative for FIP1L1-PDGFRA, depending on other test results, the person may have another type of myeloproliferative or myelodysplastic neoplasm or may be diagnosed with HES without a specific cause (idiopathic). FIP1L1-PDGFRA-negative cases of HES do not respond as well to imatinib except for rare cases with PDGFRB rearrangement.

Keywords: HES/Leukemia; 4q12 (CHIC2) deletion; PDGFRA-FIP1L1 gene rearrangement; FIP1-like-1/platelet-derived growth factor alpha; FIP1L1-PDGFRA Fusion by FISH or RT-PCR.

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