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Description:Adult-onset type II citrullinemia (CTLN2), an ausomal recessive disorder, is characterized clinically by episodes of neurological symptoms associated with hyperammonemia involving disorientation, aggression, irritability, hyperactivity, seizures, coma, and potentially death from brain edema. The disease is caused by citrin deficiency. Citrin is a mitochondrial aspartate glutamate carrier (SLC25A13, a calcium dependent mitochondrial solute carrier) primarily expressed in the liver, heart, and kidney. Mutations in the SLC25A13 gene have been identified in patients with adult onset type II citrullinemia and neonates with idiopathic hepatitis (also called neonatal intrahepatic cholestasis) caused by citrin deficiency (NICCD) due to the different clinical features from the adult patients. The CT carrier frequency of heterozygous SLC25A13 mutation in Japanese population is approximately 1/69. Mutations in SLC25A13 gene have also been described in the Caucasian population, although the incidence is low. The gene contains 18 exons and is located on chromosome 7. Reasons for Referral:
Testing Methodology:A PCR-based assay is used to amplify all exons and the immediately adjacent intronic regions of the SLC25A13 gene. Direct sequence analysis of PCR products is performed in both the forward and reverse directions using automated fluorescent dideoxy sequencing methods. Specimen Requirements:Blood: EDTA (purple-top) tubes: Adult: 14 cc; Child: 6 cc; Infant: 2-3 cc Turnaround Time:Index: 4 weeks CPT Codes and Prices:
Index: 83904x36, 83898x18, 83912, 83891, 83894x2 Shipping InformationForms:>> Gene
Sequencing Requisition or Mitochondrial
Requisition - Mitochondrial Diagnostic Checklist is included References:1. Saheki T et al. (2004) Adult-onset type II citrullinemia and idiopathic neonatal hepatitis caused by citrin deficiency: involvement of the aspartate glutamate carrier for urea synthesis and maintenance of the urea cycle. Mol. Genet. Metab. 81: S20-S26. Test Codes:Index: 3155 |