Alagille AMPLIFIED™
Alagille Syndrome (AGS) is an autosomal dominant multisystem
disorder causing cholestasis due to bile duct paucity, cardiac defects, anterior chamber defects of the eye, butterfly vertebrae or other skeletal abnormalities, and characteristic facial features.
PrintAlagille Syndrome (AGS) is an autosomal dominant multisystem
disorder causing cholestasis due to bile duct paucity, cardiac defects, anterior chamber defects of the eye, butterfly vertebrae or other skeletal abnormalities, and characteristic facial features.
It is caused by mutations in the JAG1 gene. Penetrance is high, but diagnosis may be complicated by the large proportion of de novo mutations (50-70%) and highly variable clinical expression even within the same family.
Alagille AMPLIFIED provides the highest detection rate possible while controlling costs through a reflex pathway. Alagille AMPLIFIED consists of sequence analysis of JAG1, with reflex to deletion/duplication testing of JAG1 if sequence analysis is negative. Approximately 95% of AGS patients have mutations detectable by Alagille AMPLIFIED; about 88% are detected through sequence analysis of JAG1 and, if negative, about 7% are detected by deletion/duplication testing of JAG1. Alagille AMPLIFIED can also be performed concurrently by request.
For patients JAG1 who have previously had sequencing with negative results, testing for only deletions and duplications is available. Gene Sequence Analysis without reflex to deletion/duplication testing is available by request. Specific mutation analysis for individual JAG1 mutations known to be in the family is also available.
Alagille Syndrome (AGS) is a multisystem disorder with an estimated incidence of at least 1/70,000. Diagnostic criteria require three of the following five major features: cholestasis due to bile duct paucity, cardiac defect (oftenpulmonic stenosis or tetralogy of Fallot), anterior chamber defects of the eye (especially posterior embryotoxon), butterfly vertebrae or other skeletal abnormalities, and characteristic facial features.1,2 Less frequent findings include functional and structural defects of the kidneys, pancreatic insufficiency, and vascular abnormalities. Most patients are diagnosed in infancy. Mortality is 10% with early deaths due to cardiac or severe liver disease and late mortality from vascular accidents.1
Alagille Syndrome is caused by heterozygous dominant mutations in the JAG1 gene (also called JAGGED1). Penetrance is high, but diagnosis may be complicated by the large proportion of de novo mutations (50-70%) and highly variable clinical expression even within the same family. Severity ranges from multisystem involvement with critical liver or cardiac disease, to isolated cardiac defects, to subclinical vertebral or facial changes.2 Therefore, evaluation of first degree relatives of a proband should be considered. Approximately 95% of AGS patients have mutations detectable by the Ambry Test through sequence analysis of JAG1 (~88%) and further testing for gross gene deletions and duplications (~7%).3 The NOTCH2 gene, which is not included in Alagille AMPLIFIED, accounts for less than 1% of AGS4.
Molecular testing provides a highly sensitive tool for diagnostic confirmation in symptomatic individuals, testing of at-risk family members who are asymptomatic or have subclinical features, and prenatal testing of at-risk pregnancies.
Genomic deoxyribonucleic acid (gDNA) is isolated from the patients specimen using a standardized kit and quantified by agarose gel electrophoresis. If the Ambry Test: Allagille AMPLIFIED is requested, two methods are employed as indicated: 1) polymerase chain reaction (PCR) to selectively amplify regions of gDNA corresponding to the JAG1 gene and double stranded sequencing in sense and antisense directions to detect sequence variations, and if indicated 2) gross deletion/duplication analysis using the Multiplex Ligation-Dependent Probe Amplification (MLPA) kit, developed by MRC Holland. If specific mutation analysis is requested, only specific region(s) of DNA is (are) amplified by PCR and sequenced. If gross deletion/duplication analysis is requested, including analysis for a specific familial deletion or duplication, the MLPA kit will be used to analyze the entire gene.
As stated above, full gene sequence analysis is expected to detect mutations in about 88% of affected patients. Additional testing for gross deletions and duplications detects mutations in approximately 7% of patients, for an overall Alagille AMPLIFIED detection rate of ~95% (clinical sensitivity). The Alagille AMPLIFIED test detects ~99% of described disease-causing mutations in JAG1 (analytic sensitivity).
Blood Samples:
Container: Purple top EDTA tube (preferred) or yellow top citric acetate tube.
Amount: Adult 3-5 cc, pediatric 2 cc minimum.
Storage: 2-8°C. Do not freeze.
Shipment: Room temperature for two-day delivery.
Transfusion Patients: Wait at least two weeks after a packed cell or platelet transfusion and at least four weeks after a whole blood transfusion prior to blood draw.
DNA:
Container: Sterile plastic tube.
Amount: min. 20 μg of DNA in TE (10mM Tris-Cl pH 8.0, 1mM EDTA); preferred 200 μl at ~100 ng/μl.
For specific mutation(s) analysis: min. 5 μg of DNA (~100 ng/μl conc.).
Please provide DNA OD 260-280 ratio (preferred 1.7-1.9) and send agarose picture with high mw genomic DNA, if available.
Storage: -20°C.
Shipment: Shipment frozen on dry ice is preferred, or ship on ice.
For Transfusion Patients: Wait at least two weeks after a packed cell or platelet transfusion and at least four weeks after a whole blood transfusion prior to blood draw.
Blood Spots:
Container: Schleicher + Schuell (S&S) 903 specimen collection paper.
Amount: Minimum of one complete spot of approximately 0.5 inch in diameter.
Storage: Room temperature in a sterile bag.
Shipment: 2-8°C up to 72 hours. Do not freeze.
Saliva:
Container: Oragene DNA Self Collection container.
Amount: 2 ml.
Storage: At room temperature in sterile bag.
Shipment: Ship room temperature for two-day delivery
Prenatal:
Prenatal testing is available. Please call an Ambry Genetic Counselor to discuss your case.
| Test Code | Technique | CPT Codes |
|---|---|---|
| 1640 | JAG1 Gene Sequence Analysis and Deletion / Duplication | 83891x1, 83894x26, 83898x25, 83904x48, 83900x1, 83901x24, 83909x48, 83912x2 |
| 1641 | JAG1 Deletion / Duplication Analysis | 83891x1, 83894x1, 83900x1, 83901x24, 83909x1, 83912x1 |
| 1643 | JAG1 Gene Sequence Analysis | 83891x1, 83894x26, 83898x25, 83904x48, 83909x48, 83912x1 |
| Technique | Days |
|---|---|
| JAG1 Gene Sequence Analysis and Deletion / Duplication | 10-28 |
| JAG1 Deletion / Duplication Analysis | 10-21 |
| JAG1 Gene Sequence Analysis | 7-14 |
1 Emerick KM et al. Hepatology. 1999;29:822-829.
2 Kamath BM et al. J Med Genet. 2003;40:891-895.
3 Warthen DM et al. Hum Mutation. 2006;27:436-443.
4 McDaniell R et al. Am J Hum Genet. 2006;79:169-173.