APOL1 test: G1 and G2 alleles

About this test

The APOL1 test is a genotyping test which detects variants that comprise the G1 (NM_001136540:c.1024A>G, p.Ser342Gly and NM_001136540:c.1152T>G, p.Ile384Met) and G2 (NM_001136540:c.1160_1165delATAATT) risk alleles. The APOL1 test can be ordered by a physician as a tool in the counseling, evaluation and management of their patients.

The African-American population has a total lifetime risk of ~0.8% (1 in 125) to develop focal segmental glomerulosclerosis (FSGS). The G1 and G2 alleles of APOL1 increase the risk. The aggregate frequency of either of these two alleles in African-Americans is about 35% (1 in 3 individuals). For those persons with 0 risk alleles, the risk of developing FSGS is 0.2%; for persons with 1 risk allele, it is 0.3%; and for persons with 2 risk alleles, it is 4.25% (Kopp, JB., et al., J Am Soc Nephrol. 2011 Nov;22(11):2129-37).

Indications for testing

Common indications for testing include:

Determining the risk status of patients, especially the African-American and Caribbean population, including:

  • Those with kidney disease believed to be due to hypertension, FSGS, SLE, membranous GN or HIV
  • Patients being considered for kidney donation
  • Determining carrier status in a family member related to an APOL1 carrier

How to order this test

  1. This test must be ordered by a health care provider. Please note patients are not permitted to order the test.
  2. Complete the PDF iconrequisition:
    1. UIHC health care providers should complete a PDF iconrequisition form and place a miscellaneous testing order in Epic titled 'APOL1 test'. This is a send out test.
    2. Health care providers outside of the University of Iowa Hospitals and Clinics may order the test by mailing the completed PDF iconrequisition form and sample to the address listed below.
  3. See Specimen type for sample collection information.
  4. After collection, samples should be stored and shipped at room temperature.
  5. Delivery: will receive Monday-Friday. Do not ship for delivery on weekends or US holidays.

IIHG Clinical Diagnostic Division

285 Newton Road, 5292 CBRB

Iowa City, IA 52242-1078

Specimen type

*All samples must be labeled with the patient's name, date of birth, and date of collection

  • ~6ml whole blood in lavender EDTA tube (~3ml pediatric minimum)

OR

  • 3μg DNA (A260/A280 1.8-2) re-suspended in 0.1mM EDTA (10mM Tris HCl, 0.1mM EDTA, pH 8, Teknova Cat# T0220)

After collection, samples should be stored and shipped at room temperature for delivery Monday-Friday. The IIHG does not receive samples on weekends or US holidays.

Please note: if insufficient quality or quantity of DNA is obtained, an additional sample will be requested. Incorrect handling or shipping can result in insufficient DNA quality or quantity.

Turnaround time

~5 business days after receipt of the sample and test requisition at the IIHG lab.

Cost, billing, and CPT code

  • Your institution will be billed $200 for this test. The IIHG will NOT submit to insurance or bill patients directly. Insurance may, or may not, cover this test. Please check with the patient's insurance provider for current coverage.
  • The IIHG accepts institutional billing, Visa and MasterCard.
  • This test corresponds with CPT code 81479.

Methodology

DNA extraction, then PCR amplification of APOL1 exon 6, followed by Sanger sequencing.

These tests were developed and their performance characteristics determined by the Clinical Diagnostic Division of the Iowa Institute of Human Genetics. These tests have not been cleared or approved by the US Food and Drug Administration (FDA).

Resources

The IIHG can help with the following:

  • Determining if this test is appropriate for your patient.
  • Understanding the result report and result interpretation.
  • Contact: 319-335-3688 or iihg@uiowa.edu.
  • If you would like an appointment or to refer a patient to our UIHC Rare Kidney Disease Clinic, click here.

Data storage

  • Experimental data are kept for a minimum of six years.
  • The final report is kept indefinitely.

Technical limitations

  • The APOL1 genotype assay has been limited to the evaluation of known variants within exon 6 of the APOL1 gene. Additional APOL1 gene variants will not be identified. Variants in other genes are not detectable with this assay. Rare sequence variants within primer sites may lead to erroneous results.
  • This test cannot predict disease onset or severity.

Frequently asked questions

  • What certifications does the IIHG have?
  • Is this test FDA approved?

    • These tests were developed and their performance characteristics determined by the Clinical Diagnostics Division of the Iowa Institute of Human Genetics. These tests have not been cleared or approved by the US Food and Drug Administration. (21 CFR§ 809.30 [e]. The FDA does not require this test to go through pre-market FDA review. This test is used for clinical purposes. It should not be regarded as investigational or for research. This laboratory is certified under the Clinical Laboratory Improvement Amendments (CLIA) as qualified to perform high complexity clinical laboratory testing.

  • Do I need to order a test kit prior to ordering the test?

    • No, the PDF iconrequisition can be downloaded from our website, and standard lavender (EDTA) tubes can be used.

  • How was the cost of the test determined?

    • Cost was determined based on resources used, reagents, machine usage, data storage, and labor.

  • Does the IIHG perform insurance verification/pre-authorization?

    • No, at this time the IIHG does not perform insurance verification/pre-authorization.

  • Do you accept credit card billing or direct patient payment?

    • The IIHG accepts institutional billing, Visa and MasterCard.

  • Is this test covered by insurance?

    • APOL1 genotype testing may or may not be covered. Pre-authorization is recommended so that you can explain to the provider why APOL1 testing is needed.

  • Can I get my patient’s results faster than the published turnaround time?

    • At this time there is no preferential treatment of any samples.

  • How are results returned to me?

    • Results will be returned to the ordering physician and genetic counselor by fax or secure email.

  • What is reported?

    • The APOL1 genotyping assay has been limited to the evaluation of known variants within exon 6 of the APOL1 gene. Additional APOL1 gene variants will not be identified. Variants in other genes are not detectable with this assay. Rare sequence variants within primer sites may lead to erroneous results.

  • Will the report contain medical advice?

    • No, the report does not contain medical advice, as the ordering physician will need to interpret the test results within the clinical context.

  • Will the IIHG send me brochures for my clinic?