Citrullinemia, Type I (ASS1) Sequencing

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.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Counseling and informed consent are recommended for genetic testing. Consent forms are available online.