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.
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 Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81406

Components
Component Test Code* Component Chart Name LOINC
2007070 Citrullinemia, Type I (ASS1)Seq Specimen 31208-2
2007071 Citrullinemia, Type I (ASS1) Seq Interp 50398-7
* 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
Citrullinemia, Type I (ASS1) Sequencing