FIP1L1-PDGFRA
- Also Known As:
- HES/Leukemia
- 4q12 (CHIC2) deletion
- PDGFRA-FIP1L1 gene rearrangement
- FIP1-like-1/platelet-derived growth factor alpha
- Formal Name:
- FIP1L1-PDGFRA Fusion by FISH or RT-PCR

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.At a Glance
Why Get Tested?
To help investigate the cause of hypereosinophilia (HE), a condition with persistent increase in the number of eosinophils, a specific type of white blood cell, or hypereosinophilic syndrome (HES), which is HE with associated tissue or organ damage; to help determine if someone with HE or HES can be treated with a tyrosine kinase inhibitor (TKI) such as imatinib
When To Get Tested?
After complete blood counts (CBC) indicate that you have persistently elevated eosinophils and your healthcare practitioner has ruled out other causes such as allergies, parasitic infection, or medication; at regular intervals when you are being treated for HE or HES with imatinib
Sample Required?
A blood sample drawn from a vein or a bone marrow sample collected using a bone marrow aspiration and/or biopsy procedure
Test Preparation Needed?
None
What is being tested?
FIP1L1-PDGFRA is an abnormal fusion gene sequence that causes the bone marrow to produce too many 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 to help diagnose these conditions.
While some genetic abnormalities are inherited from our parents, they can also come from changes that occur to genes or chromosomes later in life. These are called somatic mutations, which can occur through exposure to various environmental factors (e.g., radiation, certain chemicals), but more often for unknown reasons.
The FIP1LI-PDGFRA gene sequence is one of those genetic changes acquired later in life. It occurs when the chromosome 4 loses approximately 800 nucleotides (DNA building blocks), which normally separate the FIP1L1 and PDGFRA genes. Because of this deletion, the two genes are brought together (fused), producing a new fusion gene. Other types of mutations can also lead to abnormalities of the PDGFRA gene, but this deletion is the most common.
Normally, the PDGFRA gene provides instructions for making a protein that controls processes like cell growth and division. When the FIP1L1-PDGFRA fusion gene is present, the gene sequence still provides instructions for making that protein, but the protein that results is abnormal because it is always activated and continues to send signals for growth and division. With constant signals for growth, eosinophils (and sometimes other blood cells) can grow out of control, causing hypereosinophilia (HE) and hypereosinophilic syndrome (HES), which can be fatal if not treated promptly.
Hypereosinophilia (HE) and Hypereosinophilic syndrome (HES)
Eosinophils are a type of white blood cell that are involved in allergic reactions and immune responses to certain parasites. The number of eosinophils in the blood may be elevated with these conditions. Hypereosinophilia is the prolonged overproduction of eosinophils. As increasing numbers of eosinophils move into and inflame tissues, HES develops. HES results when these eosinophils affect and damage a variety of organs, including the heart, lungs and the nervous system.
Common symptoms include chest pain and shortness of breath if the heart is involved. People with HES may also have anemia or excessive clotting (hypercoaguability), stroke, blurred vision or slurred speech. Other symptoms may involve the digestive tract or the skin. Sometimes, there may be no symptoms, when tissue or organ damage is less severe.
There are several causes of HE and HES besides genetic abnormalities. Allergic diseases are the most common cause in the developed world. Parasitic diseases, certain cancers, autoimmune disorders, skin disease, inflammatory bowel syndrome, and Addison disease can also cause HES. If an individual has HES and a healthcare practitioner has ruled out these secondary (reactive) causes, genetic testing can determine if FIP1L1-PDGFRA or other genetic abnormality is the underlying cause. If the genetic abnormality is detected, the HE or HES is neoplastic.
Only 0.4% of people with persistently high numbers of eosinophils carry the FIP1L1-PDGFRA gene. It is most common in individuals between 20 and 50 years old. Although it is a rare cause of HE and HES, it is important to identify it because HE/HES with FIP1L1-PDGFRA can be fatal if not treated. It can be effectively treated with the drug imatinib.
Common Questions
View Sources
Sources Used in Current Review
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Sources Used in Previous Reviews
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