Polycythaemia vera

Haematolymphoid Tumours (WHO Classification, 5th ed.)

editContent Update To WHO 5th Edition Classification Is In Process; Content Below is Based on WHO 4th Edition Classification

This page was converted to the new template on 2023-12-07. The original page can be found at HAEM4:Polycythemia Vera (PV).

(General Instructions – The focus of these pages is the clinically significant genetic alterations in each disease type. This is based on up-to-date knowledge from multiple resources such as PubMed and the WHO classification books. The CCGA is meant to be a supplemental resource to the WHO classification books; the CCGA captures in a continually updated wiki-stye manner the current genetics/genomics knowledge of each disease, which evolves more rapidly than books can be revised and published. If the same disease is described in multiple WHO classification books, the genetics-related information for that disease will be consolidated into a single main page that has this template (other pages would only contain a link to this main page). Use HUGO-approved gene names and symbols (italicized when appropriate), HGVS-based nomenclature for variants, as well as generic names of drugs and testing platforms or assays if applicable. Please complete tables whenever possible and do not delete them (add N/A if not applicable in the table and delete the examples); to add (or move) a row or column in a table, click nearby within the table and select the > symbol that appears. Please do not delete or alter the section headings. The use of bullet points alongside short blocks of text rather than only large paragraphs is encouraged. Additional instructions below in italicized blue text should not be included in the final page content. Please also see Author_Instructions and FAQs as well as contact your Associate Editor or Technical Support.)

Primary Author(s)*

Gokce A. Toruner, MD, PhD

UT MD Anderson Cancer Center

WHO Classification of Disease

Structure	Disease
Book	Haematolymphoid Tumours (5th ed.)
Category	Myeloid proliferations and neoplasms
Family	Myeloproliferative neoplasms
Type	Myeloproliferative neoplasms
Subtype(s)	Polycythaemia vera

WHO Essential and Desirable Genetic Diagnostic Criteria

(Instructions: The table will have the diagnostic criteria from the WHO book autocompleted; remove any non-genetics related criteria. If applicable, add text about other classification systems that define this entity and specify how the genetics-related criteria differ.)

WHO Essential Criteria (Genetics)*
WHO Desirable Criteria (Genetics)*
Other Classification

*Note: These are only the genetic/genomic criteria. Additional diagnostic criteria can be found in the WHO Classification of Tumours.

Related Terminology

(Instructions: The table will have the related terminology from the WHO autocompleted.)

Acceptable
Not Recommended

Gene Rearrangements

Put your text here and fill in the table (Instructions: Details on clinical significance such as prognosis and other important information can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Driver Gene	Fusion(s) and Common Partner Genes	Molecular Pathogenesis	Typical Chromosomal Alteration(s)	Prevalence -Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: ABL1	EXAMPLE: BCR::ABL1	EXAMPLE: The pathogenic derivative is the der(22) resulting in fusion of 5’ BCR and 3’ABL1.	EXAMPLE: t(9;22)(q34;q11.2)	EXAMPLE: Common (CML)	EXAMPLE: D, P, T	EXAMPLE: Yes (WHO, NCCN)	EXAMPLE: The t(9;22) is diagnostic of CML in the appropriate morphology and clinical context (add reference). This fusion is responsive to targeted therapy such as Imatinib (Gleevec) (add reference). BCR::ABL1 is generally favorable in CML (add reference).
EXAMPLE: CIC	EXAMPLE: CIC::DUX4	EXAMPLE: Typically, the last exon of CIC is fused to DUX4. The fusion breakpoint in CIC is usually intra-exonic and removes an inhibitory sequence, upregulating PEA3 genes downstream of CIC including ETV1, ETV4, and ETV5.	EXAMPLE: t(4;19)(q25;q13)	EXAMPLE: Common (CIC-rearranged sarcoma)	EXAMPLE: D		EXAMPLE: DUX4 has many homologous genes; an alternate translocation in a minority of cases is t(10;19), but this is usually indistinguishable from t(4;19) by short-read sequencing (add references).
EXAMPLE: ALK	EXAMPLE: ELM4::ALK Other fusion partners include KIF5B, NPM1, STRN, TFG, TPM3, CLTC, KLC1	EXAMPLE: Fusions result in constitutive activation of the ALK tyrosine kinase. The most common ALK fusion is EML4::ALK, with breakpoints in intron 19 of ALK. At the transcript level, a variable (5’) partner gene is fused to 3’ ALK at exon 20. Rarely, ALK fusions contain exon 19 due to breakpoints in intron 18.	EXAMPLE: N/A	EXAMPLE: Rare (Lung adenocarcinoma)	EXAMPLE: T		EXAMPLE: Both balanced and unbalanced forms are observed by FISH (add references).
EXAMPLE: ABL1	EXAMPLE: N/A	EXAMPLE: Intragenic deletion of exons 2–7 in EGFR removes the ligand-binding domain, resulting in a constitutively active tyrosine kinase with downstream activation of multiple oncogenic pathways.	EXAMPLE: N/A	EXAMPLE: Recurrent (IDH-wildtype Glioblastoma)	EXAMPLE: D, P, T

editv4:Chromosomal Rearrangements (Gene Fusions)

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None

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editv4:Clinical Significance (Diagnosis, Prognosis and Therapeutic Implications).

Please incorporate this section into the relevant tables found in:

• Chromosomal Rearrangements (Gene Fusions)
• Individual Region Genomic Gain/Loss/LOH
• Characteristic Chromosomal Patterns
• Gene Mutations (SNV/INDEL)

Diagnosis

• Major criteria
  • Hemoglobin >16.5 g/dL in men or > 16 g/dL in women; or hematocrit >49% in men or > 48% in women or increased red blood cell mass
  • Bone marrow tri-lineage proliferation with Pleomorphic mature megakaryocytes.
  • Presence of JAK2 V617F mutation or JAK2 exon 12 mutations.

• Minor criterion:

·        Subnormal serum erythropoietin level 

For the diagnosis either all major criteria or first two major criteria and minor criterion should be fulfilled.

Prognosis

• Adverse factors for leukemic transformation
  • Advanced age
  • Leukocytosis
  • Abnormal karyotype (occur in progressive stages)
  • AXL1, SRF2, IDH1, IDH2, RUNX1 mutations.

• Adverse prognostic factors for thrombosis
  • Advanced age
  • History of thrombosis

Therapeutic implications

• Low risk (Age <60 years and no history of thrombosis)
  • Phlebotomy to maintain hematocrit below 45%
  • Low dose-aspirin

• High risk
  • In addition to phlebotomy and aspirin, cytoreductive therapy (hydroxyurea of peginterferon alfa-2a.)
  • For inadequate or loss of response with cytoreductive threapy: ruxolitinib or clinical trials

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Individual Region Genomic Gain/Loss/LOH

Put your text here and fill in the table (Instructions: Includes aberrations not involving gene rearrangements. Details on clinical significance such as prognosis and other important information can be provided in the notes section. Can refer to CGC workgroup tables as linked on the homepage if applicable. Please include references throughout the table. Do not delete the table.)

Chr #	Gain, Loss, Amp, LOH	Minimal Region Cytoband and/or Genomic Coordinates [Genome Build; Size]	Relevant Gene(s)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: 7	EXAMPLE: Loss	EXAMPLE: chr7	EXAMPLE: Unknown	EXAMPLE: D, P	EXAMPLE: No	EXAMPLE: Presence of monosomy 7 (or 7q deletion) is sufficient for a diagnosis of AML with MDS-related changes when there is ≥20% blasts and no prior therapy (add reference).  Monosomy 7/7q deletion is associated with a poor prognosis in AML (add references).
EXAMPLE: 8	EXAMPLE: Gain	EXAMPLE: chr8	EXAMPLE: Unknown	EXAMPLE: D, P		EXAMPLE: Common recurrent secondary finding for t(8;21) (add references).
EXAMPLE: 17	EXAMPLE: Amp	EXAMPLE: 17q12; chr17:39,700,064-39,728,658 [hg38; 28.6 kb]	EXAMPLE: ERBB2	EXAMPLE: D, P, T		EXAMPLE: Amplification of ERBB2 is associated with HER2 overexpression in HER2 positive breast cancer (add references). Add criteria for how amplification is defined.

editv4:Genomic Gain/Loss/LOH

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Frequent cytogenetic abnormalities are listed below.

Chromosome Number	Gain/Loss/Amp/LOH	Region
1	Gain	1q
8	Gain	+8
9	Gain	+9
20	Loss	20q

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Characteristic Chromosomal or Other Global Mutational Patterns

Put your text here and fill in the table (Instructions: Included in this category are alterations such as hyperdiploid; gain of odd number chromosomes including typically chromosome 1, 3, 5, 7, 11, and 17; co-deletion of 1p and 19q; complex karyotypes without characteristic genetic findings; chromothripsis; microsatellite instability; homologous recombination deficiency; mutational signature pattern; etc. Details on clinical significance such as prognosis and other important information can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Chromosomal Pattern	Molecular Pathogenesis	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE: Co-deletion of 1p and 18q	EXAMPLE: See chromosomal rearrangements table as this pattern is due to an unbalanced derivative translocation associated with oligodendroglioma (add reference).	EXAMPLE: Common (Oligodendroglioma)	EXAMPLE: D, P
EXAMPLE: Microsatellite instability - hypermutated		EXAMPLE: Common (Endometrial carcinoma)	EXAMPLE: P, T

editv4:Characteristic Chromosomal Aberrations / Patterns

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Cytogenetic abnormalities is present about 20% of the cases (see genomic gain/loss/LOH section). Associated with progression and adverse prognosis.

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Gene Mutations (SNV/INDEL)

Put your text here and fill in the table (Instructions: This table is not meant to be an exhaustive list; please include only genes/alterations that are recurrent or common as well either disease defining and/or clinically significant. If a gene has multiple mechanisms depending on the type or site of the alteration, add multiple entries in the table. For clinical significance, denote associations with FDA-approved therapy (not an extensive list of applicable drugs) and NCCN or other national guidelines if applicable; Can also refer to CGC workgroup tables as linked on the homepage if applicable as well as any high impact papers or reviews of gene mutations in this entity. Details on clinical significance such as prognosis and other important information such as concomitant and mutually exclusive mutations can be provided in the notes section. Please include references throughout the table. Do not delete the table.)

Gene	Genetic Alteration	Tumor Suppressor Gene, Oncogene, Other	Prevalence - Common >20%, Recurrent 5-20% or Rare <5% (Disease)	Diagnostic, Prognostic, and Therapeutic Significance - D, P, T	Established Clinical Significance Per Guidelines - Yes or No (Source)	Clinical Relevance Details/Other Notes
EXAMPLE:EGFR	EXAMPLE: Exon 18-21 activating mutations	EXAMPLE: Oncogene	EXAMPLE: Common (lung cancer)	EXAMPLE: T	EXAMPLE: Yes (NCCN)	EXAMPLE: Exons 18, 19, and 21 mutations are targetable for therapy. Exon 20 T790M variants cause resistance to first generation TKI therapy and are targetable by second and third generation TKIs (add references).
EXAMPLE: TP53; Variable LOF mutations	EXAMPLE: Variable LOF mutations	EXAMPLE: Tumor Supressor Gene	EXAMPLE: Common (breast cancer)	EXAMPLE: P		EXAMPLE: >90% are somatic; rare germline alterations associated with Li-Fraumeni syndrome (add reference). Denotes a poor prognosis in breast cancer.
EXAMPLE: BRAF; Activating mutations	EXAMPLE: Activating mutations	EXAMPLE: Oncogene	EXAMPLE: Common (melanoma)	EXAMPLE: T

Note: A more extensive list of mutations can be found in cBioportal, COSMIC, and/or other databases. When applicable, gene-specific pages within the CCGA site directly link to pertinent external content.

editv4:Gene Mutations (SNV/INDEL)

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• JAK2 V617F mutations
  • Highly frequent, but not diagnostic for PV, as more than half of Essential Throbocythemia and Primary Myelofibrosis have JAK2 V617F.
  • This mutation is located in the pseudokinase domain of the JAK2 protein

• JAK2 exon 12 mutations
  • Located in the so called linked region (amino acids 536- 547) between the SRC2 homology (SH2) and pseudokinase domains.
  • Most of these mutations are in frame indels .
  • Associated with younger age, increased hemoglobulin and hematocrit levels and lower WBC compated to cases with JAK2 V617F mutations

Gene	Mutation	Oncogene/Tumor Suppressor/Other	Presumed Mechanism (LOF/GOF/Other; Driver/Passenger)	Prevalence (COSMIC/TCGA/Other)
JAK2	V617F	Oncogene	GOF; Driver	95-97%
JAK2	Exon 12 mutations	Oncogene	GOF; Driver	3%

Other Mutations

Most frequent mutations other than JAK2 in PV are TET2 and ASXL1 .

Type	Gene/Region/Other
Concomitant Mutations	TET2, ASXL1, SH2B3, CEBPA, ZRSR2,S3FB1,CSF3R,KITSRSF2,IDH2,DNMT3A,SUZ12.SETB1,RUNX1.CBL,TP53,FLT3

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Epigenomic Alterations

Methylation of promoter regions has not been documented, but mutations of genes important in epigenetic regulation are observed

Genes and Main Pathways Involved

Put your text here and fill in the table (Instructions: Please include references throughout the table. Do not delete the table.)

Gene; Genetic Alteration	Pathway	Pathophysiologic Outcome
EXAMPLE: BRAF and MAP2K1; Activating mutations	EXAMPLE: MAPK signaling	EXAMPLE: Increased cell growth and proliferation
EXAMPLE: CDKN2A; Inactivating mutations	EXAMPLE: Cell cycle regulation	EXAMPLE: Unregulated cell division
EXAMPLE: KMT2C and ARID1A; Inactivating mutations	EXAMPLE: Histone modification, chromatin remodeling	EXAMPLE: Abnormal gene expression program

editv4:Genes and Main Pathways Involved

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• JAK2 is physically bound to homodimeric receptors: EPOR, MPL and G-CSFR and act as the catalytic part of these receptors upon the binding of the cytokine to the receptor.
• JAK2 V617F mutation results in non-cytokine dependent constitutive phosphorylation and activation of the down-stream STAT molecules and Pl3K and MAPK pathways.

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Genetic Diagnostic Testing Methods

• Complete blood count
• Bone marrow aspiration and biopsy with trichrome reticulin stain
• NGS panels including JAK2 gene analysis
• Chromosome analysis and FISH
• Serum erythropoietin levels.

Familial Forms

• Geographical clustering in Pennsylvania  and Quebec were observed
• JAK2 46/1 haplotype has been suggested for genetic predisposition
• A whole exome study on a multi-generation family from Finland suggest several candidate SNPs
• As of July 2020, a known family with an unequivocal high penetrance mutation has not been documented.

Additional Information

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Links

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References

(use the "Cite" icon at the top of the page) (Instructions: Add each reference into the text above by clicking where you want to insert the reference, selecting the “Cite” icon at the top of the wiki page, and using the “Automatic” tab option to search by PMID to select the reference to insert. If a PMID is not available, such as for a book, please use the “Cite” icon, select “Manual” and then “Basic Form”, and include the entire reference. To insert the same reference again later in the page, select the “Cite” icon and “Re-use” to find the reference; DO NOT insert the same reference twice using the “Automatic” tab as it will be treated as two separate references. The reference list in this section will be automatically generated and sorted.)

Notes

*Primary authors will typically be those that initially create and complete the content of a page.  If a subsequent user modifies the content and feels the effort put forth is of high enough significance to warrant listing in the authorship section, please contact the Associate Editor or other CCGA representative.  When pages have a major update, the new author will be acknowledged at the beginning of the page, and those who contributed previously will be acknowledged below as a prior author.

Prior Author(s):

*Citation of this Page: “Polycythaemia vera”. Compendium of Cancer Genome Aberrations (CCGA), Cancer Genomics Consortium (CGC), updated 02/11/2025, https://ccga.io/index.php/HAEM5:Polycythaemia_vera.