Test Id : HEMP
Hereditary Erythrocytosis Mutations, Whole Blood
Useful For
Suggests clinical disorders or settings where the test may be helpful
Definitive evaluation of an individual with JAK2-negative erythrocytosis associated with lifelong sustained increased red blood cell (RBC) mass, elevated RBC count, hemoglobin, or hematocrit
This test is not intended for prenatal diagnosis.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
This test is a third-order test and should be ordered when the patient meets the following criteria: diagnosis of erythrocytosis and JAK2 V617F is negative.
Profile Information
A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MINT | Molecular Interpretation | No | Yes |
| EPOR | EPOR Gene, Mutation Analysis, B | No | Yes |
| HIF2A | HIF2A Gene, Mutation Analysis, B | No | Yes |
| PHD2 | PHD2 Gene, Mutation Analysis, B | No | Yes |
Additional Tests
Lists tests that are always performed, at an additional charge, with the initial tests.
| Test Id | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| BPGMM | BPGM Full Gene Sequencing | Yes | Yes |
| VHLE | VHL Gene Erythrocytosis Mutations | No, (Order VHLZZ) | Yes |
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This evaluation is recommended for patients presenting with lifelong erythrocytosis, usually with a positive family history of similar symptoms. Polycythemia vera should be excluded prior to testing as it is much more common than hereditary erythrocytosis and can be present even in young patients. A JAK2 V617F or JAK2 exon 12 variant should not be present. Additionally, testing to exclude the possibility of a high oxygen affinity hemoglobin variant should be performed before ordering this test. See Ordering Guidance.
Additional testing for BPGM full gene sequencing and VHL gene erythrocytosis variant analysis will always be performed at an additional charge.
For more information see Erythrocytosis Evaluation Testing Algorithm
Method Name
A short description of the method used to perform the test
Polymerase Chain Reaction (PCR) Amplification/Sanger Sequence Analysis
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
EGLN1
HIF
PHD
EPAS1
EPOR
Erythrocytosis
Polycythemia
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This evaluation is recommended for patients presenting with lifelong erythrocytosis, usually with a positive family history of similar symptoms. Polycythemia vera should be excluded prior to testing as it is much more common than hereditary erythrocytosis and can be present even in young patients. A JAK2 V617F or JAK2 exon 12 variant should not be present. Additionally, testing to exclude the possibility of a high oxygen affinity hemoglobin variant should be performed before ordering this test. See Ordering Guidance.
Additional testing for BPGM full gene sequencing and VHL gene erythrocytosis variant analysis will always be performed at an additional charge.
For more information see Erythrocytosis Evaluation Testing Algorithm
Specimen Type
Describes the specimen type validated for testing
Whole blood
Ordering Guidance
For a complete evaluation including hemoglobin electrophoresis testing and hereditary erythrocytosis variant analysis in an algorithmic fashion, order REVE2 / Erythrocytosis Evaluation, Blood.
This test does not provide a serum erythropoietin (EPO) level. If EPO testing is desired, order EPO / Erythropoietin, Serum.
Necessary Information
Erythrocytosis Patient Information (T694) is strongly recommended, but not required, to be filled out and sent with the specimen. This information aids in providing a more thorough interpretation of test results. Ordering providers are strongly encouraged to complete the form and send it with the specimen.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Container/Tube: Lavender top (EDTA)
Specimen Volume: 3 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. Erythrocytosis Patient Information (T694)
3. If not ordering electronically, complete, print, and send a Benign Hematology Test Request Form (T755) with the specimen.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Moderately to severely clotted | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated (preferred) | 30 days | |
| Ambient | 14 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Definitive evaluation of an individual with JAK2-negative erythrocytosis associated with lifelong sustained increased red blood cell (RBC) mass, elevated RBC count, hemoglobin, or hematocrit
This test is not intended for prenatal diagnosis.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
This test is a third-order test and should be ordered when the patient meets the following criteria: diagnosis of erythrocytosis and JAK2 V617F is negative.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
This evaluation is recommended for patients presenting with lifelong erythrocytosis, usually with a positive family history of similar symptoms. Polycythemia vera should be excluded prior to testing as it is much more common than hereditary erythrocytosis and can be present even in young patients. A JAK2 V617F or JAK2 exon 12 variant should not be present. Additionally, testing to exclude the possibility of a high oxygen affinity hemoglobin variant should be performed before ordering this test. See Ordering Guidance.
Additional testing for BPGM full gene sequencing and VHL gene erythrocytosis variant analysis will always be performed at an additional charge.
For more information see Erythrocytosis Evaluation Testing Algorithm
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Erythrocytosis (ie, increased red blood cell [RBC] mass or polycythemia) may be primary, due to an intrinsic defect of bone marrow stem cells (ie, polycythemia vera: PV), or secondary, in response to increased serum erythropoietin (EPO) levels. Secondary erythrocytosis is associated with a number of disorders including chronic lung disease, chronic increase in carbon monoxide (due to smoking), cyanotic heart disease, high-altitude living, kidney cysts and tumors, hepatoma, and other EPO-secreting tumors. When these common causes of secondary erythrocytosis are excluded, a heritable cause involving hemoglobin or erythrocyte regulatory mechanisms may be suspected.
Unlike polycythemia vera, hereditary erythrocytosis is not associated with the risk of clonal evolution and should present with isolated erythrocytosis that has been present since birth. A small subset of cases are associated with pheochromocytoma or paraganglioma formation. Hereditary erythrocytosis is caused by variations in several genes and may be inherited in either an autosomal dominant or autosomal recessive manner. A family history of erythrocytosis would be expected in these cases, although it is possible for new variants to arise in an individual.
The genes coding for hemoglobin, beta globin and alpha globin (high-oxygen-affinity hemoglobin variants), hemoglobin-stabilization proteins (2,3 bisphosphoglycerate mutase: BPGM), and the erythropoietin receptor(EPOR) and oxygen-sensing pathway enzymes (hypoxia-inducible factor[HIF/EPAS1], prolyl hydroxylase domain [PHD2/EGLN1], and von Hippel Lindau [VHL]) can result in hereditary erythrocytosis (see Table). The true prevalence of hereditary erythrocytosis-causing variants is unknown. The hemoglobin genes, HBA1/HBA2 and HBB are not assayed in this profile.
Table. Genes Associated with Hereditary Erythrocytosis
| Gene | Inheritance | Serum EPO |
| JAK2 V617F | Acquired | Decreased |
| JAK2 exon 12 | Acquired | Decreased |
| EPOR | Dominant | Decreased |
| PHD2/EGLN1 | Dominant | Normal level |
| BPGM | Recessive | Normal level |
| Beta globin | Dominant | Normal level to increased |
| Alpha globin | Dominant | Normal level to increased |
| HIF2A/EPAS1 | Dominant | Normal level to increased |
| VHL | Recessive | Normal to increased |
The oxygen-sensing pathway functions through an enzyme, HIF, which regulates RBC mass. A heterodimer protein comprised of alpha and beta subunits, HIF functions as a marker of depleted oxygen concentration. When present, oxygen becomes a substrate mediating HIF-alpha subunit degradation. In the absence of oxygen, degradation does not take place and the alpha protein component is available to dimerize with a HIF-beta subunit. The heterodimer then induces transcription of many hypoxia response genes including EPO, VEGF, and GLUT1. HIF-alpha is regulated by VHL protein-mediated ubiquitination and proteosomal degradation, which requires prolyl hydroxylation of HIF proline residues. The HIF-alpha subunit is encoded by the HIF2A (EPAS1) gene. Enzymes important in the hydroxylation of HIF-alpha are the prolyl hydroxylase domain proteins, of which the most significant isoform is PHD2, which is encoded by the PHD2 (EGLN1) gene. Variations resulting in altered HIF-alpha, PHD2, and VHL proteins can lead to clinical erythrocytosis. A small subset of variants in PHD2/EGLN1 and HIF2A/EPAS1 have also been detected in erythrocytic patients presenting with paragangliomas or pheochromocytomas.
Truncating variants in the EPOR gene coding for the erythropoietin receptor can result in erythrocytosis through loss of the negative regulatory cytoplasmic SHP-1 binding domain leading to EPO hypersensitivity. All currently known variants have been localized to exon 8 and are heterozygous truncating variants. EPOR variants are associated with decreased EPO levels (see Table).
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
An interpretive report will be provided.
Interpretation
Provides information to assist in interpretation of the test results
An interpretive report will be provided and will include specimen information, assay information, and whether the specimen was positive for any variants in the gene. If positive, the variant will be correlated with clinical significance, if known.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Polycythemia vera and acquired causes of erythrocytosis should be excluded before ordering this evaluation.
This test will not detect somatic or gonadal mosaicism.
Certain sequence alterations have no clinical manifestations and, in essence, are clinically benign. Correlation with all relevant clinical information is necessary to provide appropriate patient care.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Patnaik MM, Tefferi A: The complete evaluation of erythrocytosis: congenital and acquired. Leukemia. 2009 May;23(5):834-844. doi: 10.1038/leu.2009.54
2. McMullin MF: The classification and diagnosis of erythrocytosis. Int J Lab Hematol. 2008 Dec;30(6):447-459. doi: 10.1111/j.1751-553X.2008.01102.x
3. Percy MJ, Lee FS: Familial erythrocytosis: molecular links to red blood cell control. Haematologica. 2008 Jul;93(7):963-967. doi: 10.3324/haematol.13250
4. Huang LJ, Shen YM, Bulut GB: Advances in understanding the pathogenesis of primary familial and congenital polycythaemia. Br J Haematol. 2010 Mar;148(6):844-852. doi: 10.1111/j.1365-2141.2009.08069.x
5. Maran J, Prchal J: Polycythemia and oxygen sensing. Patho Biol. 2004 Jun;52(5):280-284. doi: 10.1016/j.patbio.2004.02.006
6. Lee F: Genetic causes of erythrocytosis and the oxygen-sensing pathway. Blood Rev. 2008 Nov;22(6):321-332. doi: 10.1016/j.blre.2008.04.003
7. Merchant SH, Oliveira JL, Hoyer JD, Viswanatha DS: Erythrocytosis. In: His ED, ed. Hematopathology. 2nd ed. Elsevier Saunders; 2012:22-723
8. Zhuang Z, Yang C, Lorenzo F, et al: Somatic HIF2A gain-of-function mutations in paraganglioma with polycythemia. N Engl J Med. 2012 Sep 6;367(10):922-930. doi: 10.1056/NEJMoa1205119
9. Ladroue C, Carcenac R, Leporrier M, et al: PHD2 mutation and congenital erythrocytosis with paraganglioma. N Engl J Med. 2008 Dec 18;359(25):2685-2692. doi: 10.1056/NEJMoa0806277
10. Lorenzo FR, Yang C, Ng Tang Fui M, et al: A novel EPAS1/HIF2A germline mutation in congenital polycythemia with paraganglioma. J Mol Med. 2013 Apr;91(4):507-512. doi: 10.1007/s00109-012-0967-z
11. Tarade D, Robinson CM, Lee JE, Ohh M: HIF-2alpha-pVHL complex reveals broad genotype-phenotype correlations in HIF-2aalpha-driven disease. Nat Commun. 2018 Aug;9(1):3359. doi: 10.1038/s41467-018-05554-1
12. Oliveira JL: Algorithmic evaluation of hereditary erythrocytosis: Pathways and caveats. Int J Lab Hematol. 2019 May;41 Suppl 1:89-94. doi: 10.1111/ijlh.13019
Method Description
Describes how the test is performed and provides a method-specific reference
DNA is extracted from whole blood and amplified in 7 separate polymerase chain reaction (PCR) to cover EPOR exon 8, HIF2A exons 9 and 12, and PHD2 exons 1 through 5. PCR products are then sequenced by the Sanger sequencing method and analyzed with sequencing software. Patient sequence results are compared with the genomic reference sequences and the single nucleotide variants known to occur in the genes. If a variant is detected, the messenger RNA reference sequence will be used to determine the amino acid number and resulting amino acid change, if there is one.(Percy MJ, McMullin MF, Roques AW, et al: Erythrocytosis due to a mutation in the erythropoietin receptor gene. Br J Haematol. 1998 Feb;100:407-410. doi: 10.1046/j.1365-2141.1998.00550.x; Martini M, Teofili L, Cenci T, et al: A novel heterozygous HIF2a[M535I] mutation reinforces the role of oxygen sensing pathway disturbances in the pathogenesis of familial erythrocytosis. Haematologica. 2008;93[7]:1068-1071. doi: 10.3324/haematol.13210; Percy MJ, Zhao Q, Flores A, et al: A family with erythrocytosis establishes a role for prolyl hydroxylase domain protein 2 in oxygen homeostasis. PNAS 2006;103[3]:654-659. doi: 10.1073/pnas.0508423103; Oliveira JL, Coon LM, Frederick LA, et al: Genotype-phenotype correlation of hereditary erythrocytosis mutations, a single center experience. Am J Hematol. 2018 May 23. doi: 10.1002/ajh.25150)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Friday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
81479
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| HEMP | Hereditary Erythrocytosis Mut, B | 105351-1 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 34645 | EPOR Gene Sequencing Result | 82939-0 |
| 34646 | PHD2 Gene Sequencing Result | 82939-0 |
| 34647 | HIF2A Gene Sequencing Result | 82939-0 |
| 34648 | Molecular Interpretation | 69047-9 |
| 35000 | Reviewed By | 18771-6 |