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Test Code ALPGP Alport Syndrome Gene Panel, Varies


Ordering Guidance


Customization of this panel and single gene analysis for any gene present on this panel are available. For more information see CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies.

 

Targeted testing for familial variants (also called site-specific or known mutations testing) is available for the genes on this panel. See FMTT / Familial Variant, Targeted Testing, Varies. To obtain more information about this testing option, call 800-533-1710.



Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Specimen Required


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.

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

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)/Refrigerated


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. Hereditary Renal Genetic Testing Patient Information (T918)

3. If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.

Secondary ID

618044

Useful For

Providing a genetic evaluation for patients with a personal or family history suggestive of Alport syndrome 

 

Establishing a diagnosis of Alport syndrome

Method Name

Sequence Capture Next-Generation Sequencing (NGS)/Sanger Sequencing

Reporting Name

Alport Syndrome Gene Panel

Specimen Type

Varies

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Reject Due To

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

Clinical Information

Alport syndrome (AS) is a genetic disorder characterized by kidney disease, sensorineural hearing loss, and ocular findings. The disease spectrum, severity, and progression are variable; in many cases, kidney disease progresses to kidney failure.(1)

 

The genes associated with AS form the collagen IV alpha 345 network of basement membranes and have 3 different modes of inheritance. Disease-causing variants in the COL4A5 gene cause X-linked AS (XLAS) and account for approximately two thirds of disease.(1) In hemizygous male patients, XLAS tends to be more severe, while heterozygous female patients typically have a milder presentation (usually only hematuria).(2)

 

Autosomal recessive AS (ARAS) accounts for approximately 15% of cases and is caused by biallelic disease-causing variants in COL4A3 or COL4A4.(3) Some carriers of ARAS may develop thin basement membrane nephropathy. Digenic inheritance with disease-causing variants in both COL4A3 and COL4A4 has also been reported.(4) Autosomal dominant AS, caused by heterozygous disease-causing variants in COL4A3 or COL4A4, accounts for approximately 20% of cases and tends to exhibit slower disease progression (1,5)

 

Large deletions that span the adjacent 5' ends of COL4A5 and COL4A6 are associated with a contiguous gene syndrome characterized by AS and diffuse leiomyomatosis in the esophagus, however, disease-causing COL4A6 variants do not appear to be associated with isolated Alport syndrome.(6)

Reference Values

An interpretive report will be provided.

Interpretation

All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(7) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Method Description

Next-generation sequencing (NGS) and Sanger sequencing are performed to test for the presence of variants in coding regions and intron/exon boundaries of the genes analyzed, as well as some other regions that have known disease-causing variants. The human genome reference GRCh37/hg19 build was used for sequence read alignment. At least 99% of the bases are covered at a read depth over 30X. Sensitivity is estimated at above 99% for single nucleotide variants, above 94% for deletions-insertions (delins) less than 40 base pairs (bp), above 95% for deletions up to 75 bp and insertions up to 47 bp. NGS and/or a polymerase chain reaction based quantitative method is performed to test for the presence of deletions and duplications in the genes analyzed.

 

There may be regions of genes that cannot be effectively evaluated by sequencing or deletion and duplication analysis as a result of technical limitations of the assay, including regions of homology, high guanine-cytosine (GC) content, and repetitive sequences. See Targeted Genes and Methodology Details for Alport Syndrome Gene Panel for details regarding the targeted genes analyzed for each test and specific gene regions not covered.(Unpublished Mayo method)

 

Confirmation of select reportable variants may be performed by alternate methodologies based on internal laboratory criteria.

 

Genes analyzed: COL4A3, COL4A4, COL4A5, COL4A6

Day(s) Performed

Varies

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

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

81407

81408 x 2

81479 (if appropriate for government payers)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALPGP Alport Syndrome Gene Panel 51966-0

 

Result ID Test Result Name Result LOINC Value
618045 Test Description 62364-5
618046 Specimen 31208-2
618047 Source 31208-2
618048 Result Summary 50397-9
618049 Result 82939-0
618050 Interpretation 69047-9
618051 Additional Results 82939-0
618052 Resources 99622-3
618053 Additional Information 48767-8
618054 Method 85069-3
618055 Genes Analyzed 48018-6
618056 Disclaimer 62364-5
618057 Released By 18771-6