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).
Polymerase Chain Reaction/Sequencing
Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
Transport 3 mL whole blood. (Min: 1 mL)
Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
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.
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.
Laboratory Developed Test (LDT)
|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|
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