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).
- 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
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.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
Component Test Code* | Component Chart Name | LOINC |
---|---|---|
2007070 | Citrullinemia, Type I (ASS1)Seq Specimen | |
2007071 | Citrullinemia, Type I (ASS1) Seq Interp |
- Argininosuccinate Synthetase Deficiency (ASS1) Sequencing
- Argininosuccinic Acid Synthetase Deficiency (ASS1) Sequencing
- ASS Deficiency (ASS1) Sequencing
- ASS1 Sequencing
- CTLN1 (ASS1) Sequencing