Test Catalog

Test Id : APOL1

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APOL1 Genotype, Varies

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Overview

Test Catalog

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

Determining an individual’s APOL1 genotype

 

This test is not useful for clinical management of individuals with APOL1 risk genotypes.

 

This test alone is not useful for determining eligibility for donation or receipt of kidney allografts.(12)

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

Real-Time Polymerase Chain Reaction (PCR) with Allelic Discrimination Analysis

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

APOL1 Genotype, V

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

G2

G1

ESRD

End-stage renal disease

CKD

Chronic kidney disease

APOL1

Apolipoprotein L1

Specimen Type
Describes the specimen type validated for testing

Varies

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

Submit only 1 of the following specimens:

 

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.

Specimen Stability Information: Ambient (preferred) 9 days/Refrigerated 30 days

 

Specimen Type: Saliva

Patient Preparation: Patient should not eat, drink, smoke, or chew gum 30 minutes prior to collection.

Supplies: Saliva Swab Collection Kit (T786)

Specimen Volume: 1 swab

Collection Instructions: Collect and send specimen per kit instructions.

Specimen Stability Information: Ambient 30 days

 

Specimen Type: Extracted DNA

Container/Tube: 2 mL screw top tube

Specimen Volume: 100 mcL (microliters)

Collection Instructions:

1. The preferred volume is 100 mcL at a concentration of 50 ng/mcL.

2. Include concentration and volume on tube.

Specimen Stability Information: Frozen (preferred)/Ambient/Refrigerated

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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) 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.

Blood: 0.4 mL

Saliva/DNA: See Specimen Required

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

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
Varies Varies

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

Determining an individual’s APOL1 genotype

 

This test is not useful for clinical management of individuals with APOL1 risk genotypes.

 

This test alone is not useful for determining eligibility for donation or receipt of kidney allografts.(12)

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The APOL1 gene encodes apolipoprotein L-1, a serum apolipoprotein bound to high-density lipoprotein (HDL) particles. Two alleles, commonly called G1 and G2, have been associated with increased risk for development or progression of nondiabetic chronic kidney diseases, including HIV-associated nephropathy (HIVAN), primary focal segmental glomerulosclerosis (FSGS), and lupus-associated collapsing glomerulopathy.(1-4) The G1 allele is a haplotype consisting of 2 missense variants: c.1024A>G (p.Ser342Gly) and c.1152T>G (p.Ile384Met). The G2 allele is comprised of a 6 base pair deletion that results in the deletion of 2 amino acids: c.1164_1169delTTATAA (p.Asn388_Tyr389del). The G1 and G2 alleles are thought to be in complete linkage disequilibrium, meaning when both the G1 and G2 alleles are detected, they are on opposite chromosomes.(1) Risk for chronic kidney disease is only increased when 2 risk alleles are inherited (ie, genotypes G1/G1, G2/G2, or G1/G2), following an autosomal recessive pattern of inheritance.(1) Individuals with one risk allele or no risk alleles do not appear to be at an increased risk.

 

The G1 and G2 risk alleles are enriched in individuals of African ancestry. Population studies show that in individuals of African descent, the G1 allele is found on 20% to 22.5% of chromosomes, and the G2 allele is found on 13% to 15% of chromosomes.(5-6) More importantly, it is estimated that 10% to15% of individuals of African descent carry 2 risk alleles.(5-6) The high frequency of the G1 and G2 alleles in this population is likely due to the protective effect these alleles confer against Trypanosoma rhodesiense, a parasite that causes trypanosomiasis, a disease endemic to Africa.(1) The G1 and G2 alleles are extremely rare or absent in individuals not of recent African descent (eg, European and Asian descent).(1,5) For this reason, increased risk associated with the G1 and G2 alleles has only been stratified in populations of recent African ancestry, and it remains unclear if similar risk effects associated with the APOL1 risk genotypes are applicable to individuals without African ancestry. Currently, there are no guidelines for clinical management of individuals with APOL1 risk genotypes.

 

Evidence exists that the donor APOL1 genotype may impact both donor and recipient outcomes of kidney allografts. Results from 2 studies have shown that donor kidneys from individuals with 2 risk alleles were more likely to fail after transplantation when compared to donor kidneys from individuals with one or no risk alleles.(7-8) Another study suggests that living donors with two risk alleles may be at an increased risk for reduced kidney function following kidney donation.(9) At this time, there has been no association between the genotype of the allograft recipient and transplant outcomes, suggesting that allograft recipients with two risk alleles have similar outcomes to recipients with one or no risk alleles.(10) However, a prospective, large scale study to assess kidney allograft survival from donors with recent African ancestry based on donor and recipient APOL1 genotypes is currently ongoing.(11) Based on presently available data, guidelines advise that an individual’s APOL1 genotype alone should not determine eligibility for donation or receipt of kidney allografts.(12)

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.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This assay will not detect all variants associated with an increased risk for development or progression of a chronic kidney disease. Therefore, the absence of an APOL1 risk genotype does not rule out the possibility that an individual is at an increased risk for development or progression of a chronic kidney disease.

 

Specific APOL1 genotypes are associated with an increased lifetime risk for chronic kidney diseases. Currently, there are no guidelines for clinical management of individuals with APOL1 risk genotypes.

 

The APOL1 genotype of a kidney donor may be associated with worsened outcomes in the allograft recipient. However. this assay cannot predict or rule out the development or progression of a chronic kidney disease in an individual. Current guidelines advise that an individual’s APOL1 genotype alone should not determine eligibility for donation or receipt of kidney allografts.(12)

 

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in the interpretation of results may occur if information given is inaccurate or incomplete.

 

Rare alterations may be present that could lead to false-negative or false-positive results. This assay does not identify less common apolipoprotein L1 alleles. Thus, an individual who appears to be homozygous for G1 or G2 may carry a rare allele that cannot be detected by this assay. If results obtained do not match the clinical findings, additional testing should be considered.

 

In rare cases, DNA variants of undetermined significance may be identified.

 

Specimens may contain donor DNA if obtained from patients who received heterologous blood transfusions or allogeneic hematopoietic stem cell transplantation. Results from specimens obtained under these circumstances may not accurately reflect the recipient's genotype. For individuals who have received blood transfusions, the genotype usually reverts to that of the recipient within 6 weeks. For individuals who have received allogeneic hematopoietic stem cell transplantation, a pretransplant DNA specimen is recommended for testing.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Genovese G, Friedman DJ, Ross MD, et al: Association of trypanolytic ApoL1 variants with kidney disease in African Americans. Science. 2010;329(5993):841-845. doi: 10.1126/science.1193032

2. Parsa A, Kao WH, Xie D, et al: APOL1 risk variants, race, and progression of chronic kidney disease. N Engl J Med. 2013;369(23):2183-2196. doi: 10.1056/NEJMoa1310345

3. Kopp JB, Nelson GW, Sampath K, et al: APOL1 genetic variants in focal segmental glomerulosclerosis and HIV-associated nephropathy. J Am Soc Nephrol. 2011;22(11):2129-2137. doi: 10.1681/ASN.2011040388

4. Larsen CP, Beggs ML, Saeed M, Walker PD: Apolipoprotein L1 risk variants associate with systemic lupus erythematosus-associated collapsing glomerulopathy. J Am Soc Nephrol. 2013;24(5):722-725. doi: 10.1681/ASN.2012121180

5. Friedman DJ, Kozlitina J, Genovese G, Jog P, Pollak MR: Population-based risk assessment of APOL1 on renal disease. J Am Soc Nephrol. 2011;22(11):2098-2105. doi: 10.1681/ASN.2011050519

6. Duran CE, Ramírez A, Posada JG, et al: Prevalence of APOL1 risk variants in afro-descendant patients with chronic kidney disease in a Latin American Country. Int J Nephrol. 2019 Dec 18;2019:7076326. doi: 10.1155/2019/7076326

7. Reeves-Daniel AM, DePalma JA, Bleyer AJ, et al: The APOL1 gene and allograft survival after kidney transplantation. Am J Transplant. 2011;11(5):1025-1030. doi: 10.1111/j.1600-6143.2011.03513.x

8. Freedman BI, Julian BA, Pastan SO, et al: Apolipoprotein L1 gene variants in deceased organ donors are associated with renal allograft failure. Am J Transplant. 2015;15(6):1615-1622. doi: 10.1111/ajt.13223

9. Doshi MD, Ortigosa-Goggins M, Garg AX, et al: APOL1 genotype and renal function of black living donors. J Am Soc Nephrol. 2018;29(4):1309-1316. doi: 10.1681/ASN.2017060658

10. Lee BT, Kumar V, Williams TA, et al: The APOL1 genotype of African American kidney transplant recipients does not impact 5-year allograft survival. Am J Transplant. 2012;12(7):1924-1928. doi: 10.1111/j.1600-6143.2012.04033.x

11. Freedman BI, Moxey-Mims MM, Alexander AA, et al: APOL1 long-term kidney transplantation outcomes network (APOLLO): Design and rationale. Kidney Int Rep. 2019;5(3):278-288. doi: 10.1016/j.ekir.2019.11.022

12. Newell KA, Formica RN, Gill JS, et al: Integrating APOL1 gene variants into renal transplantation: Considerations arising from the American Society of Transplantation Expert Conference. Am J Transplant. 2017;17(4):901-911. doi: 10.1111/ajt.14173

Method Description
Describes how the test is performed and provides a method-specific reference

Genomic DNA is extracted from whole blood. Genotyping for each allele is performed using a polymerase chain reaction (PCR)-based 5'-nuclease assay. Fluorescently labeled detection probes anneal to the target DNA. PCR is used to amplify the section of DNA that contains the variant. If the detection probe is an exact match to the target DNA, the 5'-nuclease polymerase degrades the probe, the reporter dye is released from the effects of the quencher dye, and a fluorescent signal is detected.(Unpublished Mayo method)

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.

3 to 8 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/Saliva swab: 2 weeks; Extracted DNA: 2 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.

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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
APOL1 APOL1 Genotype, V 104664-8
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.
610559 APOL1 Result 104664-8
610561 Interpretation 69047-9
610562 Additional Information 48767-8
610563 Method 85069-3
610564 Disclaimer 62364-5
610565 Reviewed by 18771-6

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 | 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