• Test Code:
    1275
  • Department:
    Molecular Genetics
  • Test Synonyms:
    Alagille syndromeCongenital Bile Acid Synthesis DefectFamilial Intrahepatic CholestasisPeroxisome Biogenesis DisorderZellweger Syndrome
  • CPT Code(s):
    81407
Background:

Although jaundice is relatively common in the neonatal period, persistent jaundice is abnormal. When it persists beyond the second week of life, cholestasis or conjugated hyperbilirubinemia may be considered. Cholestasis is defined by impaired bilirubin excretion resulting in excess conjugated bilirubin in the bloodstream and decreased bile salts in the GI tract. This impaired flow of bile can be caused by an intrahepatic or extrahepatic disorder. Infants may present with jaundice, dark urine (containing conjugated bilirubin), hepatosplenomegaly, poor weight gain, and hypopigmented or acholic stools.

Cholestasis has many etiologies. It is estimated that the most common causes of neonatal cholestasis are biliary atresia (25-35%), genetic disorders (25%) and metabolic diseases (20%). Genetic testing may confirm a diagnosis of a genetic disorder, which may affect medical management or treatment of the condition. It is recommended that this testing be accompanied by a complete family history and genetic counseling.

Reasons for Referral:

  • Molecular confirmation of a clinical diagnosis
  • To aid in decision-making for treatment and management of individuals with inherited cholestatic diseases.
  • Testing for individuals with a positive family history for inherited cholestasis (targeted testing is available if the familial mutation is known).

Methodology:

Next generation sequencing will analyze the exons or coding regions of 65 Cholestasis-associated genes using Illumina NextSeq 500 technology.  Samples are prepared using hybridization probes to enrich exonic regions.  Promoter, intronic, etc. regions are not assessed on our assay, but may contain variants that impact gene function.

The 65 Cholestasis-associated genes are listed below:
ABCB11, ABCB4, ABCC2, ABCG5, ABCG8, AKR1D1, ALDOB, AMACR, ATP8B1, BAAT, CC2D2A, CFTR, CLDN1, CYP27A1, CYP7A1, CYP7B1, DCDC2, DGUOK, DHCR7, FAH, GPBAR1, HNF1B, HSD17B4, HSD3B7, INVS, JAG1, LIPA, MKS1, MPV17, NOTCH2, NPC1, NPC2, NPHP1, NPHP3, NPHP4, NR1H4, PEX1, PEX10, PEX11B, PEX12, PEX13, PEX14, PEX16, PEX19, PEX2, PEX26, PEX3, PEX5, PEX6, PEX7, PKHD1, POLG, SCP2, SERPINA1, SLC10A1, SLC10A2, SLC25A13, SLC27A5, SMPD1, TJP2, TMEM216, TRMU, UGT1A1, VIPAS39, VPS33B

Specimen Requirements:

Blood:  EDTA or ACD (Solution A or B):

  • Adult: 5 mL
  • Child: 5 mL
  • Infant: 2-3 mL

Saliva: 2 ORAgene™ Saliva Collection Kit(s) (OGR-500) used according to manufacturer instructions. Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.

Skin Fibroblast: Punch Biopsy (Cell cultures will be prepared at KDL and used for testing), or 2 T-25 confluent flasks

Prenatal:

  • Direct Amniotic Fluid (10-20mL)
  • Direct CVS
  • Cultured Amnio or CVS (2-T25 flasks)

DNA: 10µg at a minimum of 60-100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)

Notice Regarding Molecular Genetic Testing on CVS or Amniotic Fluid Specimens:

  • Maternal cell rule-out testing will be performed on all prenatal specimens received. Please provide maternal blood in addition to the fetal specimen. Additional charges apply for the maternal cell rule-out test.
  • All genetic testing performed on Direct CVS or Amniotic Fluid specimens will be confirmed on cell cultures prepared by Knight Diagnostic Laboratories. Cell cultures will be prepared from the specimen received. Additional charges apply for confirmatory testing.

For routine testing of blood, saliva and buccal swabs, KDL does NOT accept samples from patients within two (2) weeks of a packed cell/platelet transfusion or within four (4) weeks of a whole blood transfusion.  For extraordinary circumstances, where testing must be performed outside of the above windows, please contact our lab.

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information, including ethnicity, clinical history, and family history.

Test Performed (Days):

Weekly

Turn Around Time:

8 weeks

Shipment Sensitivity Requirements:

  • Package and ship specimen to remain cold, but not frozen. 
  • Ship via overnight express, using the FedEx priority overnight label provided. 
  • Contact Client Services for shipping kits and instructions at (855) 535-1522.

References:

  1. Balistreri WF, Bezerra JA. Whatever happened to “neonatal hepatitis.” Clin Liver Dis. 2006;10(1):27–53.
  2. Feldman AG, Sokol RJ. Neonatal Cholestasis. NeoReviews. 2013;14(2):63-73.14-2-e63.

Additional Info: