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Citrullinemia, Type I (ASS1) Sequencing
2007069
Ordering Recommendation

Molecular (DNA) test to confirm a diagnosis of citrullinemia type I following clinical and/or biochemical presentation. To diagnose or rule out citrullinemia type I, refer to Amino Acids Quantitative by LC-MS/MS, Plasma (2009389).

Mnemonic
ASS1 FGS
Methodology
Polymerase Chain Reaction/Sequencing
Performed
Varies
Reported
14-21 days
New York DOH Approval Status
Specimens from New York clients will be sent out to a New York DOH approved laboratory, if possible.
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
 
Collect
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B). 
Specimen Preparation
Transport 3 mL whole blood. (Min: 1 mL) 
Storage/Transport Temperature
Refrigerated. 
Unacceptable Conditions
 
Remarks
 
Stability
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable 
Reference Interval
Interpretive Data
Background Information for Citrullinemia, Type I (ASS1) Sequencing:
Characteristics:
Classic citrullinemia type I is a urea cycle disorder characterized by hyperammonemia, lethargy, vomiting, coma and neonatal death if not treated. There is also a milder, late-onset form and a form in which women have onset of severe symptoms during pregnancy or postpartum.
Incidence:
Approximately 1 in 57,000.
Inheritance:
Autosomal recessive.
Penetrance:
Variable.
Cause
: Pathogenic ASS1 gene mutations.
Clinical Sensitivity:
Approximately 96 percent.
Methodology:
Bidirectional sequencing of the entire ASS1 coding region and intron/exon boundaries.
Analytical Sensitivity and Specificity: 99 percent.
Limitations:
Diagnostic errors can occur due to rare sequence variations. Regulatory region mutations, deep intronic mutations, and large deletions/duplications will not be detected. Mutations in genes other than ASS1 are not evaluated.

Compliance Statement C: The performance characteristics of this test were validated by ARUP Laboratories. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing. Counseling and informed consent are recommended for genetic testing. Consent forms are available online.

Components
Component Test Code*Component Chart NameLOINC
2007070Citrullinemia, Type I (ASS1)Seq Specimen
2007071Citrullinemia, Type I (ASS1) Seq Interp
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • Argininosuccinate Synthetase Deficiency (ASS1) Sequencing
  • Argininosuccinic Acid Synthetase Deficiency (ASS1) Sequencing
  • ASS Deficiency (ASS1) Sequencing
  • ASS1 Sequencing
  • CTLN1 (ASS1) Sequencing