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Test Code ALAGP Alagille Syndrome Gene Panel, Varies


Ordering Guidance


Targeted testing for familial variants (also called site-specific or known mutations/variants 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.

 

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.



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

618030

Useful For

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

 

Establishing a diagnosis of Alagille syndrome

Method Name

Sequence Capture and Next Generation Sequencing (NGS)

Reporting Name

Alagille 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

Alagille syndrome (ALGS) is a multisystemic genetic condition with a wide spectrum of clinical variability. Characteristic features of ALGS include bile duct paucity, cholestasis, congenital heart defects, butterfly vertebrae, eye findings, and facial features including a broad forehead, deeply set eyes, and a small, pointed chin.(1) Approximately 40% of individuals also have kidney disease. The kidney features may include structural abnormalities (eg, small hyperechoic kidney, kidney cysts, or ureteropelvic obstruction) as well as kidney dysfunction, such as renal tubular acidosis.

 

Disease-causing variants in the JAG1 gene account for approximately 94% to 97% of ALGS, while disease-causing NOTCH2 gene variants account for approximately 1% to 3% of cases.(1,2) A small percentage of individuals with a clinical diagnosis of ALGS do not have an identified disease-causing variant in either JAG1 or NOTCH2.

 

The severity of ALGS is highly variable among individuals, ranging from mild and subclinical, to severe heart or liver disease requiring transplantation. ALGS is inherited in an autosomal dominant manner. Approximately 30% to 50% of individuals inherit ALGS from an affected parent, while about 50% to 70% of cases are de novo. Parental somatic mosaicism and germline mosaicism have been reported.

Reference Values

An interpretive report will be provided.

Interpretation

All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(3) 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/or 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 pathogenic 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 Alagille Syndrome Gene Panel for details regarding the targeted genes analyzed for each test and specific gene regions not routinely covered.(Unpublished Mayo method)

 

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

 

Genes analyzed: JAG1, NOTCH2

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

81479

81479 (if appropriate for government payers)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
ALAGP Alagille Syndrome Gene Panel 51966-0

 

Result ID Test Result Name Result LOINC Value
618031 Test Description 62364-5
618032 Specimen 31208-2
618033 Source 31208-2
618034 Result Summary 50397-9
618035 Result 82939-0
618036 Interpretation 69047-9
618037 Additional Results 82939-0
618038 Resources 99622-3
618039 Additional Information 48767-8
618040 Method 85069-3
618041 Genes Analyzed 48018-6
618042 Disclaimer 62364-5
618043 Released By 18771-6