Adenylosuccinase Deficiency via the ADSL Gene
Summary and Pricing 
Test Method
Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 6919 | ADSL | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.
Turnaround Time
3 weeks on average for standard orders or 2 weeks on average for STAT orders.
Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.
Targeted Testing
For ordering sequencing of targeted known variants, go to our Targeted Variants page.
Clinical Features and Genetics
Clinical Features
The adenylosuccinase enzyme (ADSL) carries out two independent steps of purine biosynthesis (Van Keuren et al., 1987). Adenylosuccinase deficiency is characterized by the accumulation of succinylamino-imidazole carboxamide riboside (SAICAr) and succinyladenosine (S-ado) in cerebrospinal fluid and urine (Jaeken and Van den Berghe, 1984). ADSL-deficient patients usually present with moderate to severe intellectual disability, often accompanied by epilepsy, autistic features (poor eye contact, repetitive behavior, temper tantrums), or both. ADSL deficiency occasionally presents with growth retardation and muscular hypotonia. Type 1 ADSL deficiencies are associated with severe to moderate psychomotor retardation, epilepsy, and autism; type 2 cases present milder forms of these symptoms. The most severe cases manifest as generalized seizures starting within the first days or weeks of life, leading to death within a few months.
Genetics
Adenylosuccinase deficiency is a rare autosomal recessive disorder caused by variants in the ADSL gene located on chromosome 22q13.1-q13.2 (Van Keuren et al., 1987; Fon et al., 1993). Although a few chain-termination variants have been reported, the great majority of causative ADSL variants are missense, resulting in amino acid substitutions (Gitiaux et al., 2009). One of the most common is c.1279G>A (p.Arg426His).
Clinical Sensitivity - Sequencing with CNV PG-Select
All of the currently documented ADSL causative mutations are detectable by sequencing (http://www.hgmd.cf.ac.uk/). However, the possibility of large deletions and other mutations which are not detectable by our sequencing test cannot be discounted. Due to the marked heterogeneity of clinical features, the overall prevalence of ADSL deficiency is currently unknown.
Testing Strategy
This test provides full coverage of all coding exons of the ADSL gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
Candidates for this test are patients with elevated levels of SAICAr or S-ado, at 100-500 μM concentration in cerebrospinal fluid, or 25-700 μmol/mmol of creatinine in urine (Stone et al., 1992). In addition, testing for adenylosuccinase deficiency has also been recommended in patients with mental retardation and a behavioral profile suggestive of Angelman syndrome (Gitiaux et al., 2009). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in ADSL.
Candidates for this test are patients with elevated levels of SAICAr or S-ado, at 100-500 μM concentration in cerebrospinal fluid, or 25-700 μmol/mmol of creatinine in urine (Stone et al., 1992). In addition, testing for adenylosuccinase deficiency has also been recommended in patients with mental retardation and a behavioral profile suggestive of Angelman syndrome (Gitiaux et al., 2009). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in ADSL.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| ADSL | 608222 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Adenylosuccinate Lyase Deficiency | AR | 103050 |
Citations
- Fon, E. A., et.al. (1993). "Mapping of the human adenylosuccinate lyase (ADSL) gene to chromosome 22q13.1-->q13.2." Cytogenet Cell Genet 64(3-4): 201-3. PubMed ID: 8404037
- Gitiaux, C., et.al. (2009). "Misleading behavioural phenotype with adenylosuccinate lyase deficiency." Eur J Hum Genet 17(1): 133-6. PubMed ID: 18830228
- Human Gene Mutation Database.
- Jaeken, J., Van den Berghe, G. (1984). "An infantile autistic syndrome characterised by the presence of succinylpurines in body fluids." Lancet 2(8411): 1058-61. PubMed ID: 6150139
- Stone, R. L., et.al. (1992). "A mutation in adenylosuccinate lyase associated with mental retardation and autistic features." Nat Genet 1(1): 59-63. PubMed ID: 1302001
- Van Keuren, M. L., et.al. (1987). "A somatic cell hybrid with a single human chromosome 22 corrects the defect in the CHO mutant (Ade-I) lacking adenylosuccinase activity." Cytogenet Cell Genet 44(2-3): 142-7. PubMed ID: 3568763
Ordering/Specimens
Ordering Options
We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.
myPrevent - Online Ordering
- The test can be added to your online orders in the Summary and Pricing section.
- Once the test has been added log in to myPrevent to fill out an online requisition form.
- PGnome sequencing panels can be ordered via the myPrevent portal only at this time.
Requisition Form
- A completed requisition form must accompany all specimens.
- Billing information along with specimen and shipping instructions are within the requisition form.
- All testing must be ordered by a qualified healthcare provider.
For Requisition Forms, visit our Forms page
If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.
Specimen Types
Specimen Requirements and Shipping Details
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ORDER OPTIONS
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