Test Catalog

Test Id : PHD2

Not Orderable

Prolyl Hydroxylase Domain-2 (PHD2/EGLN1) Gene Sequencing, Whole Blood

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Assessing PHD2/EGLN1 in the evaluation of an individual with JAK2-negative erythrocytosis associated with lifelong sustained increased red blood cell (RBC) mass, elevated RBC count, hemoglobin, or hematocrit

Method Name
A short description of the method used to perform the test

Only orderable as part of a profile. For more information see HEMP / Hereditary Erythrocytosis Mutations, Whole Blood.

 

Polymerase Chain Reaction (PCR)/Sanger Sequencing

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

PHD2 Gene, Mutation Analysis, B

Aliases
Lists additional common names for a test, as an aid in searching

EGLN1

Specimen Type
Describes the specimen type validated for testing

Whole blood

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Only orderable as part of a profile. For more information see HEMP / Hereditary Erythrocytosis Mutations, Whole Blood.

 

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

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

Assessing PHD2/EGLN1 in the evaluation of an individual with JAK2-negative erythrocytosis associated with lifelong sustained increased red blood cell (RBC) mass, elevated RBC count, hemoglobin, or hematocrit

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 variants 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 alterations 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 alterations 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 level to increased

 

The oxygen-sensing pathway functions through an enzyme, hypoxia-inducible factor (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 von Hippel-Lindau (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. Genetic variants 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 to normal EPO levels values (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.

Only orderable as part of a profile. For more information see HEMP / Hereditary Erythrocytosis Mutations, Whole Blood.

 

An interpretive report will be provided.

Interpretation
Provides information to assist in interpretation of the test results

An interpretive report will be provided as a part of the HEMP / Hereditary Erythrocytosis Mutations, Whole Blood 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

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

5. Maran J, Prchal J: Polycythemia and oxygen sensing. Pathologie Biologie. 2004 Jun;52(5):280-284

6. Lee F: Genetic causes of erythrocytosis and the oxygen-sensing pathway. Blood Rev. 2008 Nov;22(6):321-332

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

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

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

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 22;9(1):3359

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) reactions 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(2):407-410; 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; Percy MJ, Zhao Q, Flores A, et al: A family with erythrocytosis establishes a role for prolyl hydroxylase domain protein 2 in oxygen homeostasis. Proc Natl Acad Sci U S A.2006;103[3]:654-659; 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

No

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.

10 to 25 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Whole blood: 2 weeks; Extracted DNA: 3 months

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

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.

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
PHD2 PHD2 Gene, Mutation Analysis, B In Process
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.
34646 PHD2 Gene Sequencing Result 82939-0

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports