Gilbert Syndrome

CPT Code(s): 81350

Service Code (IU Health): 53104527

Ordering Recommendation: This test is intended to identify the UGT1A1*28 (g.4963_4964[7]), UGT1A1*36 (g.4963_4964[5]), and UGT1A1*37 (g.4963_4964[8]) variants in UGT1A1 from genomic DNA. Information about these variants may be used as an aid to clinicians for confirming a diagnosis of Gilbert syndrome.

Synonyms: UGT1A1, fragment analysis, Gilbert syndrome, hyperbilirubinemia

Methodology: Polymerase chain reaction (PCR) and fragment analysis with capillary electrophoresis.

Performed: Weekly

Reported: 7-10 days

Patient Preparation: Whole blood: none required; Saliva: no eating, drinking, smoking or chewing gum 30 min. prior to collection.

Collect: Preferred: Lavender (EDTA); Acceptable: Yellow (ACD Solution A or B), Green (Heparin), Saliva (Oragene collection device)

Specimen Volume: Blood: 3 mL whole blood (minimum 1 mL); Saliva: 2 mL

Storage/Transport: Refrigerated/Room temperature

Unacceptable Conditions: Grossly hemolyzed or clotted

Stability: One month refrigerated; One month frozen

Reference Interval: by report

Characteristics: Gilbert syndrome is a relatively mild condition characterized by periods of elevated levels of a toxic substance called bilirubin in the blood (hyperbilirubinemia). Bilirubin, which has an orange-yellow tint, is produced when red blood cells are broken down. This substance is removed from the body only after it undergoes a chemical reaction in the liver, which converts the toxic form of bilirubin (unconjugated bilirubin) to a nontoxic form called conjugated bilirubin. People with Gilbert syndrome have a buildup of unconjugated bilirubin in their blood (unconjugated hyperbilirubinemia). In affected individuals, bilirubin levels fluctuate and very rarely increase to levels that cause jaundice, which is yellowing of the skin and whites of the eyes.

Inheritance: Autosomal recessive

Cause: UGT1A1 allelic variants

Incidence: Gilbert syndrome is a common condition that is estimated to affect 3 to 7 percent of Americans.

Clinical sensitivity: >90%

Analytical sensitivity and specificity: 100%

Limitations: Only the targeted variants will be detected. Mutations or variants in other genes will not be detected. Although rare, false positive or false negative results may occur. All results should be interpreted in context of clinical findings, relevant history, and other laboratory data.

Alleles Tested