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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed February 2012

What is the official name of the FIP1L1 gene?

The official name of this gene is “FIP1 like 1 (S. cerevisiae).”

FIP1L1 is the gene's official symbol. The FIP1L1 gene is also known by other names, listed below.

What is the normal function of the FIP1L1 gene?

The FIP1L1 gene provides instructions for making part of a protein complex named cleavage and polyadenylation specificity factor (CPSF). This complex of proteins plays an important role in processing molecules called messenger RNAs (mRNAs), which serve as the genetic blueprints for making proteins. The CPSF protein complex helps add a string of the RNA building block adenine to the mRNA, creating a polyadenine tail or poly(A) tail. The poly(A) tail is important for stability of the mRNA and for protein production from the blueprint.

How are changes in the FIP1L1 gene related to health conditions?

PDGFRA-associated chronic eosinophilic leukemia - caused by mutations in the FIP1L1 gene

A deletion of genetic material from chromosome 4 brings together part of the FIP1L1 gene and part of another gene called PDGFRA, creating the FIP1L1-PDGFRA fusion gene. This mutation is a somatic mutation, which means it is acquired during a person's lifetime and is present only in certain cells. This fusion gene causes PDGFRA-associated chronic eosinophilic leukemia, which is a type of blood cell cancer characterized by an increased number of eosinophils, a type of white blood cell involved in allergic reactions.

The FIP1L1-PDGFRA protein produced from the fusion gene has the function of the normal PDGFRA protein, which stimulates signaling pathways inside the cell that control many important cellular processes, such as cell growth and division (proliferation) and cell survival. Unlike the normal PDGFRA protein, however, the FIP1L1-PDGFRA protein is constantly turned on (constitutively activated), which means the cells are always receiving signals to proliferate. When the FIP1L1-PDGFRA fusion gene occurs in blood cell precursors, the growth of eosinophils (and occasionally other blood cells) is poorly controlled, leading to PDGFRA-associated chronic eosinophilic leukemia. It is unclear why eosinophils are preferentially affected by this genetic change.

Where is the FIP1L1 gene located?

Cytogenetic Location: 4q12

Molecular Location on chromosome 4: base pairs 53,377,646 to 53,462,611

The FIP1L1 gene is located on the long (q) arm of chromosome 4 at position 12.

The FIP1L1 gene is located on the long (q) arm of chromosome 4 at position 12.

More precisely, the FIP1L1 gene is located from base pair 53,377,646 to base pair 53,462,611 on chromosome 4.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about FIP1L1?

You and your healthcare professional may find the following resources about FIP1L1 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the FIP1L1 gene or gene products?

  • FIP1-like 1 protein
  • hFip1
  • pre-mRNA 3'-end-processing factor FIP1
  • Rhe

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding FIP1L1?

adenine ; biomarker ; cancer ; cell ; chromosome ; chronic ; deletion ; eosinophils ; fusion gene ; gene ; leukemia ; mRNA ; mutation ; pharmacogenetics ; polyadenylation ; proliferate ; proliferation ; protein ; RNA ; somatic mutation ; specificity

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Bain BJ. Relationship between idiopathic hypereosinophilic syndrome, eosinophilic leukemia, and systemic mastocytosis. Am J Hematol. 2004 Sep;77(1):82-5. Review. (
  • Buitenhuis M, Verhagen LP, Cools J, Coffer PJ. Molecular mechanisms underlying FIP1L1-PDGFRA-mediated myeloproliferation. Cancer Res. 2007 Apr 15;67(8):3759-66. (
  • Cools J, DeAngelo DJ, Gotlib J, Stover EH, Legare RD, Cortes J, Kutok J, Clark J, Galinsky I, Griffin JD, Cross NC, Tefferi A, Malone J, Alam R, Schrier SL, Schmid J, Rose M, Vandenberghe P, Verhoef G, Boogaerts M, Wlodarska I, Kantarjian H, Marynen P, Coutre SE, Stone R, Gilliland DG. A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosinophilic syndrome. N Engl J Med. 2003 Mar 27;348(13):1201-14. (
  • OMIM: FIP1-LIKE 1 (
  • Fukushima K, Matsumura I, Ezoe S, Tokunaga M, Yasumi M, Satoh Y, Shibayama H, Tanaka H, Iwama A, Kanakura Y. FIP1L1-PDGFRalpha imposes eosinophil lineage commitment on hematopoietic stem/progenitor cells. J Biol Chem. 2009 Mar 20;284(12):7719-32. doi: 10.1074/jbc.M807489200. Epub 2009 Jan 14. (
  • Kaufmann I, Martin G, Friedlein A, Langen H, Keller W. Human Fip1 is a subunit of CPSF that binds to U-rich RNA elements and stimulates poly(A) polymerase. EMBO J. 2004 Feb 11;23(3):616-26. Epub 2004 Jan 29. (
  • NCBI Gene (
  • Roufosse FE, Goldman M, Cogan E. Hypereosinophilic syndromes. Orphanet J Rare Dis. 2007 Sep 11;2:37. Review. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: February 2012
Published: November 23, 2015