Test Catalog

Test Id : AHUSP

Complement-Mediated Atypical Hemolytic-Uremic Syndrome (aHUS)/Thrombotic Microangiopathy (TMA) Gene Panel, Varies

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

Providing a comprehensive genetic evaluation for patients with a personal or family history suggestive of complement-mediated hemolytic uremic syndrome (HUS)/atypical HUS (aHUS) or thrombotic microangiopathies (TMA)

 

Establishing a diagnosis and, in some cases, allowing for appropriate management and surveillance for disease features based on the gene involved

 

Identifying variants in genes encoding complement alternate pathway components and specific coagulation pathway genes known to be associated with increased risk for aHUS/TMA allowing for predictive testing of at-risk family members

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

This test uses next-generation sequencing to test for variants in the ADAMTS13, C3, CD46 (MCP), CFB, CFD, CFH, CFHR1, CFHR3, CFHR5, CFI, DGKE, PLG, and THBD genes.

 

This test uses Sanger sequencing to test for variants in certain exons of the following genes:

PLG Exons 1, 4, and 19

CFH Exons 20-22

CFHR1 Exons 4

CFHR3 Exons 4 and 5

 

Identification of a pathogenic variant may assist with prognosis, clinical management, familial screening, and genetic counseling.

Highlights

This test includes next-generation sequencing and supplemental Sanger sequencing to evaluate for the genes listed on the panel.

Reflex Tests
Lists tests that may or may not be performed, at an additional charge, depending on the result and interpretation of the initial tests.

Test Id Reporting Name Available Separately Always Performed
FIBR Fibroblast Culture Yes No
CRYOB Cryopreserve for Biochem Studies No No

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For skin biopsy or cultured fibroblast specimens, fibroblast culture and cryopreservation testing will be performed at an additional charge. If viable cells are not obtained, the client will be notified.

Special Instructions
Library of PDFs including pertinent information and forms related to the test

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

Custom Sequence Capture and Targeted Next-Generation Sequencing followed by Polymerase Chain Reaction (PCR) and Supplemental 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

Complement aHUS/TMA Gene Panel

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

ADAMTS13

Atypical hemolytic uremic syndrome (aHUS)

C3

CD46 (MCP)

CFB

CFD

CFH

CFHR1

CFHR3

CFHR5

CFI

Complement factor B deficiency

Complement factor D deficiency

Complement factor H deficiency

Complement factor I deficiency

DGKE

Dysplasminogenemia

Familial thrombotic thrombocytopenic purpura

Nephrotic syndrome

Plasminogen deficiency

PLG

THBD

Thrombophilia

Primary Immunodeficiency

Next Gen Sequencing Test

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For skin biopsy or cultured fibroblast specimens, fibroblast culture and cryopreservation testing will be performed at an additional charge. If viable cells are not obtained, the client will be notified.

Specimen Type
Describes the specimen type validated for testing

Varies

Ordering Guidance

Necessary Information

1. Primary Immunodeficiencies Patient Information (T791) 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.

2. Include physician name and phone number with specimen.

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

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

 

Submit only 1 of the following specimens:

 

Preferred:

Specimen Type: Whole blood

Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

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

Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated 14 days

 

Specimen Type: Blood spot

Supplies: Card-Blood Spot Collection Filter Paper (T493)

Container/Tube:

Preferred: Collection card (Whatman Protein Saver 903 Paper)

Acceptable: Whatman FTA Classic paper, Ahlstrom 226 filter paper, or Blood Spot Collection Card

Specimen Volume: 2 to 5 Blood spots on collection card

Collection Instructions:

1. An alternative blood collection option for a patient older than 1 year of age is finger stick. See Dried Blood Spot Collection Tutorial for how to collect blood spots.

2. Let blood dry on the filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

3. Do not expose specimen to heat or direct sunlight.

4. Do not stack wet specimens.

5. Keep specimen dry.

Specimen Stability Information: Ambient (preferred)/Refrigerated

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions in Special Instructions.

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777) in Special Instructions.

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800) in Special Instructions.Specimen Type: Peripheral blood mononuclear cells (PBMC)

 

Container/Tube: Cell pellet

Collection Instructions: Send as a suspension in freezing medium or cell pellet frozen on dry ice.

Specimen Stability Information: Frozen

 

Specimen Type: Cultured fibroblasts

Container/Tube: T-75 or T-25 flask

Specimen Volume: 1 Full T-75 or 2 full T-25 flasks

Specimen Stability Information: Ambient (preferred)/Refrigerated <24 hours

Additional Information: Indicate the tests to be performed on the fibroblast culture cells. A separate culture charge will be assessed under FIBR / Fibroblast Culture. An additional 4 weeks is required to culture fibroblasts before genetic testing can occur.

 

Specimen Type: Skin biopsy

Supplies: Fibroblast Biopsy Transport Media (T115)

Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin. Tubes of culture media can be supplied upon request (Eagle's minimum essential medium with 1% penicillin and streptomycin).

Specimen Volume: 4-mm punch

Specimen Stability Information: Refrigerated (preferred)/Ambient

Additional Information: A separate culture charge will be assessed under FIBR / Fibroblast Culture. An additional 4 weeks is required to culture fibroblasts before genetic testing can occur.

 

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 250 ng/mcL

2. Include concentration and volume on tube.

Specimen Stability Information: Frozen (preferred) 1 year/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 in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Primary Immunodeficiencies Patient Information (T791) is recommended. See Special Instructions.

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

-Renal Diagnostics Test Request (T830)

-Coagulation Test Request (T753)

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

Whole blood: 1 mL

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 (preferred)

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

Providing a comprehensive genetic evaluation for patients with a personal or family history suggestive of complement-mediated hemolytic uremic syndrome (HUS)/atypical HUS (aHUS) or thrombotic microangiopathies (TMA)

 

Establishing a diagnosis and, in some cases, allowing for appropriate management and surveillance for disease features based on the gene involved

 

Identifying variants in genes encoding complement alternate pathway components and specific coagulation pathway genes known to be associated with increased risk for aHUS/TMA allowing for predictive testing of at-risk family members

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

This test uses next-generation sequencing to test for variants in the ADAMTS13, C3, CD46 (MCP), CFB, CFD, CFH, CFHR1, CFHR3, CFHR5, CFI, DGKE, PLG, and THBD genes.

 

This test uses Sanger sequencing to test for variants in certain exons of the following genes:

PLG Exons 1, 4, and 19

CFH Exons 20-22

CFHR1 Exons 4

CFHR3 Exons 4 and 5

 

Identification of a pathogenic variant may assist with prognosis, clinical management, familial screening, and genetic counseling.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For skin biopsy or cultured fibroblast specimens, fibroblast culture and cryopreservation testing will be performed at an additional charge. If viable cells are not obtained, the client will be notified.

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

Complement-mediated hemolytic uremic syndrome, also known as atypical hemolytic uremic syndrome (aHUS), is a well-recognized disease entity characterized by complement activation in the microvasculature. Abnormalities of the alternate pathway of complement, which may be inherited (genetic) or acquired, underlie both the sporadic and familial forms of the disease and are identified in at least two-thirds (approximately 60%) of patients. Unlike many other monogenic disorders of the immune system, multiple hits may be required for disease manifestation, which may include a trigger event (transplantation, pregnancy, malignant hypertension, autoimmune disorders, sepsis, malignancy, etc), and 1 or more contributing genetic variants or haplotypes in the alternate pathway complement genes. The overall prognosis is poor with most patients developing end-stage kidney disease or permanent kidney injury within 1 year of diagnosis despite plasma exchange (PLEX/PEX) or plasma infusion (PI) therapy. Kidney transplantation in most patients is also associated with a poor prognosis with loss of the allograft. Drugs targeting the complement pathway, notably Eculizumab, have achieved success in modulating clinical remission and there are a few reports of combined liver-kidney transplants for these patients. Newer therapies are also likely to emerge over time. Individuals with genetic aHUS frequently experience relapse even after complete recovery following the presenting episode. Complement-mediated HUS presents with clinical features that are nearly identical to thrombotic thrombocytopenic purpura (TTP) and Shiga-toxin HUS (ST-HUS), making laboratory differentiation essential.

 

TTP is a rare clinical entity but is an important diagnosis as it is associated with very high mortality (90%) if untreated. Mortality can be reduced by early PLEX. Congenital TTP is due to genetic defects in the ADAMTS13 gene, while acquired TTP is related to autoantibodies against ADAMTS13, which reduces function. While TTP was initially characterized by thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurological signs, kidney failure and fever, the disease can present with only some of these features. The thrombotic microangiopathies (TMA) cover both aHUS and TTP and the clinical distinctions are not always clear-cut. Besides the thrombocytopenia, which is one of the key features of TMA, there is presence of schistocytes and highly increased levels of lactate dehydrogenase.

 

Complement-mediated HUS is considered genetic when 2 or more members of the same family are affected by the disease at least 6 months apart and exposure to a common triggering infectious agent has been excluded, or when pathogenic variants are identified in 1 or more of the genes known to be associated with aHUS, irrespective of familial history. A patient may have both autoantibodies to complement alternate pathway proteins and genetic defects in these genes.

 

It is important to note that certain genetic defects in these genes, eg, complement C3, may be associated with a more classic immunodeficiency phenotype with recurrent infections with encapsulated pathogens and connective tissue diseases with no evidence of aHUS/TMA.

 

Table. Genes included in this panel 

 

 

Gene symbol (alias)

Protein

OMIM

Incidence

Inheritance

Phenotype disorder

ADAMTS13

A disintegrin and metalloproteinase with thrombospondin motifs 13 isoform 1 preproprotein

604134

Not available

AR

Familial thrombotic thrombocytopenic purpura

C3

Complement C3 preproprotein

120700

Approximately 5% of aHUS

AD, AR

C3 deficiency (AR), susceptibility to aHUS (AD)

CD46 (MCP)

Membrane cofactor protein isoform 1 precursor

120920

Approximately 12% of aHUS

AD, AR

Susceptibility to aHUS 2

CFB

Complement factor B preproprotein

138470

Rare

AD

Complement factor B deficiency, susceptibility to aHUS 4

CFD

Complement factor D isoform 1 preproprotein

134350

Rare

AR

Complement factor D deficiency

CFH

Complement factor H isoform a precursor

134370

Approximately 30% of aHUS patients

AD, AR

Complement factor H deficiency, susceptibility to aHUS 1

CFHR1

Complement factor H-related protein 1 precursor

134371

Rare

AD, AR

Susceptibility to aHUS

CFHR3

Complement factor H-related protein 3 isoform 1 precursor

605336

Rare

AD, AR

Susceptibility to aHUS

CFHR5

Complement factor H-related protein 5 precursor

608593

3% of aHUS

AD

Nephropathy due to CFHR5 deficiency

CFI

Complement factor I isoform 2 preproprotein

217030

4%-10% of aHUS

AD, AR

Complement factor I deficiency (AR), susceptibility to aHUS (AD)

DGKE

Diacylglycerol kinase epsilon

601440

Rare

AR

Nephrotic syndrome Type 7, susceptibility to aHUS

PLG

Plasminogen isoform 1 precursor

173350

Rare

AR

Dysplasminogenemia, plasminogen deficiency Type I

THBD

Thrombomodulin precursor

188040

Approximately 3%-5% of aHUS

AD

Thrombophilia due to thrombomodulin defect, susceptibility to aHUS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

Evaluation and categorization of variants is performed using the most recent published American College of Medical Genetics and Genomics (ACMG) recommendations as a guideline.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

 

Multiple in silico evaluation tools may be used to assist in the interpretation of these results. The accuracy of predictions made by in silico evaluation tools is highly dependent upon the data available for a given gene, and predictions made by these tools may change over time. Results from in silico evaluation tools should be interpreted with caution and professional clinical judgment.

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

Clinical Correlations:

Some individuals who have involvement of one or more of the genes on the panel may have a variant that is not identified by the methods performed (eg, promoter variants, deep intronic variants). The absence of a variant, therefore, does not eliminate the possibility of disease. Test results should be interpreted in context of clinical findings, family history, and other laboratory data (especially complement serological analyses). Misinterpretation of results may occur if the information provided is inaccurate or incomplete.

 

Note, several genes included on this panel (C3, CFB, CFH, CFHR1, CFHR3, and CFI) have high frequency (>1%) sequence variants or haplotypes that have been identified as protective alleles or susceptibility alleles for age-related macular degeneration (ARMD). High frequency variants in these genes (>1%) are not included on this report.

 

For predictive testing of asymptomatic individuals, it is often useful to first test an affected family member. Identification of a pathogenic variant in an affected individual allows for more informative testing of at-risk individuals.

 

Technical Limitations:

Next-generation sequencing may not detect all types of genetic variants. The variant detection software has lower detection efficiency for insertion/deletion variants as compared to single nucleotide variants. Therefore, small deletions and insertions greater than 8 nucleotides in length may not be detected by this test. Copy number variations are not currently reported for any of the genes on this panel. Additionally, rare alterations (ie, polymorphisms) may be present that could lead to false-negative or false-positive results. In some cases, DNA variants of undetermined significance may be identified. If results do not match clinical findings, consider alternative methods for analyzing these genes, such as Sanger sequencing or large deletion/duplication analysis.

 

If the patient has had an allogeneic blood or bone marrow transplant or a recent (ie, <6 weeks from time of sample collection) heterologous blood transfusion, results may be inaccurate due to the presence of donor DNA. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

 

Reclassification of Variants Policy:

At this time, it is not standard practice for the laboratory to systematically review likely deleterious alterations or variants of uncertain significance that are detected and reported. The laboratory encourages health care providers to contact the laboratory at any time to learn how the status of a particular variant may have changed over time. Consultation with a healthcare provider, or team of healthcare providers, with expertise in genetics and primary immunodeficiencies, is recommended for interpretation of this result.

 

A list of benign and likely benign variants detected for this patient is available from the lab upon request.

 

Contact the laboratory if additional information is required regarding the transcript or human genome assembly used for the analysis of this patient's results.

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

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015 May;17(5):405-424

2. Picard C, Gaspar HB, Al-Herz W, et al: International Union of Immunological Societies: 2017 Primary Immunodeficiency Disease Committee Report on inborn errors of immunity. J Clin Immunol. 2018;38:96-128

3. Noris M, Bresin E, Mele C, et al: Genetic atypical hemolytic-uremic syndrome. In: Adam MP, Ardinger HH, Pagon RA, eds. GeneReviews [Internet]. University of Washington, Seattle; 2007. Updated June 9, 2016. Accessed July 2018. Available at www.ncbi.nlm.nih.gov/books/NBK1367/

4. Kavanagh D, Goodship THJ: Atypical hemolytic uremic syndrome, genetic basis and clinical manifestations. Hematology. (ASH); 2011:15-20

5. George JN, Nester CM: Syndromes of thrombotic microangiopathy. N Engl J Med. 2014;371:1654-1666

6. Go RS, Winters JL, Leung N, et al: Thrombotic Microangiopathy Care Pathway: A Consensus Statement for the Mayo Clinic Complement Alternative Pathway-Thrombotic Microangiopathy (CAP-TMA) Disease-Oriented Group. Mayo Clin Proceedings. 2016;91(9):1189-1211

Special Instructions
Library of PDFs including pertinent information and forms related to the test

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

Next-generation sequencing (NGS) is performed using an Illumina instrument with paired-end reads. The DNA is prepared for NGS using a custom Agilent SureSelect Target Enrichment System. Data is analyzed with a bioinformatics software pipeline. Supplemental Sanger sequencing is performed in select regions including CFH (exons 21-22), CFHR1 (exon 4), CFHR3 (exons 4-5) and PLG (exons 1, 4, and 19). Additional supplemental Sanger sequencing may be performed occasionally in regions where NGS is insufficient for data capture or not specific enough to correctly identify a variant.(Unpublished Mayo method)

 

Genes analyzed: ADAMTS13, C3, CD46 (MCP), CFB, CFD, CFH, CFHR1, CFHR3, CFHR5, CFI, DGKE, PLG, THBD.

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

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.

4 to 8 weeks

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

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.

  • 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 Regional Manager. 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. This test 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
AHUSP Complement aHUS/TMA Gene Panel 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.
BA3870 Gene(s) Evaluated 48018-6
BA3871 Result Summary 50397-9
BA3872 Result Details 82939-0
BA3873 Interpretation 69047-9
BA3874 Additional Information 48767-8
BA3875 Method 85069-3
BA3876 Disclaimer 62364-5
BA3877 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