Test Catalog

Test Id : FFRWB

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Friedreich Ataxia, Frataxin, Quantitative, Blood

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Overview

Test Catalog

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

Diagnosing individuals with Friedreich ataxia in whole blood specimens

 

Monitoring frataxin levels in patients with Friedreich ataxia

 

This test is not useful for carrier detection.

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Friedreich ataxia (FA) presents most commonly between 10 to 15 years of age with progressive neurologic changes including spasticity and ataxia.

 

Decreased frataxin protein levels are diagnostic of FA and can also be utilized for ongoing medical monitoring.

Highlights

Frataxin protein analysis is a quick, cost-effective test method for establishing a diagnosis of Friedreich Ataxia (FA) and will detect rare variants otherwise missed by common molecular-based trinucleotide repeat analysis.

 

This assay is available for the diagnosis of individuals with FA and monitoring frataxin levels in known patients, regardless of the individual's age.

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

Immunoassay

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

Frataxin, Quant, WB

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

Friedreich ataxia (FA)

FXN

FRDA

Frataxin

Specimen Type
Describes the specimen type validated for testing

Whole blood

Necessary Information

Provide a reason for testing with each specimen.

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

Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium or lithium heparin)

Specimen Volume: 2 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:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602)

3. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Neurology Specialty Testing Client Test Request (T732)

-Biochemical Genetics Test Request (T798)

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.

1.25 mL

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

Gross hemolysis OK
Gross lipemia OK
Gross icterus OK

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 Frozen (preferred) 70 days
Ambient 70 days
Refrigerated 70 days

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

Diagnosing individuals with Friedreich ataxia in whole blood specimens

 

Monitoring frataxin levels in patients with Friedreich ataxia

 

This test is not useful for carrier detection.

Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request

Friedreich ataxia (FA) presents most commonly between 10 to 15 years of age with progressive neurologic changes including spasticity and ataxia.

 

Decreased frataxin protein levels are diagnostic of FA and can also be utilized for ongoing medical monitoring.

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

Friedreich ataxia (FA) is an autosomal recessive disease affecting approximately 1:50,000 individuals in the white population. The disease is clinically characterized by progressive spasticity, ataxia, dysarthria, absent lower limb reflexes, sensory loss, and scoliosis. Cardiac involvement occurs with the development of myocardial fibrosis due to mitochondrial proliferation and loss of contractile proteins. It tends to be correlated with the clinical neurologic age of onset and the GAA triplet repeat length, but not the duration of disease or the severity of neurologic symptoms. Although most individuals begin experiencing initial symptoms between 10 and 15 years of age, atypical late-onset forms with initial symptoms presenting after age 25 do occur.

 

FA is caused by variants in the FXN gene encoding a mitochondrial protein, frataxin. Variants in this gene lead to a reduced expression of frataxin, which causes the clinical manifestations of the disease. Approximately 96% of individuals with FA have a homozygous expansion of the GAA trinucleotide repeat in intron 1 of FXN. The remaining 4% of FA patients have the trinucleotide expansion on 1 allele and a point alteration or deletion on the second allele. Normal alleles contain between 5 to 33 GAA repeats. Disease-causing alleles typically range from 66 to 1700 repeats, although the majority of individuals with FA have repeats ranging from 600 to 1200.

 

Historically, FA has been diagnosed by use of a DNA-based molecular test to detect the presence of the GAA expansion. Unfortunately, testing for the triplet repeat expansion will miss patients with point alterations or deletions. Moreover, a molecular-based analysis is not able to effectively monitor treatment. In contrast, this protein-based assay measuring concentration of frataxin is suitable for both diagnosis as well as treatment monitoring in individuals with FA.

 

For patients with a low frataxin level, molecular repeat expansion analysis of the FXN gene (AFXN / Friedreich Ataxia, Repeat Expansion Analysis, Varies) allows for detection of disease-causing expansion alleles.

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.

Pediatric (<18 years) normal frataxin: > or =19 ng/mL

Adults (> or =18 years) normal frataxin: > or =21 ng/mL

Interpretation
Provides information to assist in interpretation of the test results

Normal results (> or =19 ng/mL for pediatric and > or =23 ng/mL for adult patients) in properly submitted specimens are not consistent with Friedreich ataxia.

 

For results outside the normal reference range an interpretative comment will be provided.

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

No significant cautionary statements

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

1. Oglesbee D, Kroll C, Gakh O, et al. High-throughput immunoassay for the biochemical diagnosis of Friedreich ataxia in dried blood spots and whole blood. Clin Chem. 2013;59(10):1461-1469. doi:10.1373/clinchem.2013.207472

2. Deutsch EC, Oglesbee D, Greeley NR, Lynch DR. Usefulness of frataxin immunoassays for the diagnosis of Friedreich ataxia. J Neurol Neurosurg Psychiatry. 2014;85(9):994-1002

3. Delatycki MB, Bidichandani SI. Friedreich ataxia- pathogenesis and implications for therapies. Neurobiol Dis. 2019;132:104606. doi:10.1016/j.nbd.2019.104606

4. Boehm T, Scheiber-Mojdehkar B, Kluge B, Goldenberg H, Laccone F, Sturm B. Variations of frataxin protein levels in normal individuals. Neurol Sci. 2011;32(2):327-330. doi:10.1007/s10072-010-0326-1

5. Hanson E, Sheldon M, Pacheco B, Alkubeysi M, Raizada V. Heart disease in Friedreich's ataxia. World J Cardiol. 2019;11(1):1-12. doi:10.4330/wjc.v11.i1.1

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

The immunoassay utilizes frataxin-specific monoclonal antibodies bound to Luminex microspheres as capture antibodies and biotinylated frataxin-specific polyclonal antibodies as detection antibodies. Streptavidin-phycoerythrin attaches to the biotin and when exposed to light at 352 nM emits a photon that is measured and that signal is used to determine the amount of frataxin in the sample.(Oglesbee D, Kroll C, Gakh O, et al. High-throughput immunoassay for the biochemical diagnosis of Friedreich ataxia in dried blood spots and whole blood. Clin Chem. 2013;59(10):1461-1469. doi:10.1373/clinchem.2013.207472; Cowan T, Pasquali M. Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

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.

Twice per month, Thursday

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.

2 to 14 days

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

1 month

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.

83520

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
FFRWB Frataxin, Quant, WB 80979-8
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.
32253 Reason for Referral 42349-1
32254 Method 85069-3
32255 Frataxin 80979-8
32256 Interpretation 59462-2

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