Assay Sheet
Test ID
6200 Hepatitis B Virus Precore Mutations Line Probe Assay
CPT Code
83891, 83893, 83896 (x7), 83898, 83912
Clinical Utility
Mutations in the basal core promoter and precore regions can aid in the diagnosis of HBeAg-negative chronic HBV, and predict development of cirrhosis, hepatic decompensation, and hepatocellular carcinoma (HCC).1 The G1896A mutation in the precore region stops HBeAg production and the A1762T and G1764A dual mutation in the basal core promoter region down-regulates HBeAg production, both mechanisms lead to enhanced viral genome replication.2 Thus, mutations are valuable biomarkers to identify a subgroup of HBV infected individuals at extremely high risk for HCC.
Procedure
Extraction of nucleic acid from plasma or serum followed by amplification of portions of the basal core promotor and precore regions of the HBV polymerase gene. Biotinylated PCR products are hybridized to immobilized oligonucleotide probes specific to the polymorphisms in the basal core and precore region.
Note: It is recommended that 6200 Hepatitis B Precore Mutation be ordered with 1100 Hepatitis B (HBV) qPCR. HBV Precore Mutation LiPA is performed following confirmation of adequate viral load to obtain a result. If the HBV viral load is less than 1,000 IU/ml, analysis may not be successful.
Specimen type & specimen handling
Plasma: 5 to 7 ml collected in EDTA, ACD A or PPT. Minimum specimen requirement is 2ml plasma. Separate plasma from cells by centrifugation. Transfer plasma to screw-cap tube for shipment. If specimen collected in PPT tube, the entire tube can be shipped following centrifugation. Specimen may be shipped ambient or frozen.
Serum: 5 to 7 ml collected in red-top or SST. Minimum specimen requirement is 2ml serum. Separate serum from cells by centrifugation. Transfer serum to screw-cap tube for shipment. If specimen was collected in SST, the entire tube can be shipped following centrifugation. Specimen may be shipped ambient or frozen.
Causes for Rejection
Specimen types other than plasma or serum
Whole blood frozen
Specimens containing HBV DNA levels too low to allow for precore mutation testing.
Call ViraCor at 800-305-5198 if specimen is greater than 96 hrs old.
Reference values
Mutations in the HBV polymerase gene in the basal core promoter region at nt1762 and 1764 and precore region at codon 28 will be reported as detected/not detected.
Turnaround Time
Assay performed twice weekly on Mondays and Wednesdays with results reported Tuesdays and Thursdays.
Shipping
Ship Monday through Friday. Friday shipments must be labeled for Saturday delivery. All specimens must be labeled with patient's name and collection date. Multiple tests can be run on one specimen. Ship specimens FedEx Priority Overnight® to:
ViraCor Laboratories, 1001 NW Technology Dr, Lee's Summit, MO 64086
References
1. Chu CJ, Keeffe EB, Han SH, et al. Prevalence of HBV precore/core promoter variants in the United States. Hepatology. 2003;38:619-628.
2. Chan HLY, Hussain M, Lok ASF. Different hepatitis B virus genotypes are associated with different mutations in the core promoter and precore regions during hepatitis Be antigen seroconversion. Hepatology. 1999;29:976-984.
The CPT codes provided are based on ViraCor's interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. ViraCor assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material. This test is performed in a CLIA certified laboratory. FDA approval is not required for the performance of this test.
1109 V1
Pathogen Overview
ABOUT HEPATITIS B VIRUS
Hepatitis B virus (HBV) is a small, hepatotropic DNA virus. It is the prototype member of a family of closely related viruses called Hepadnaviradae. HBV is the only member of the Hepadnaviradae family that infects humans. The HBV genome is composed of a relaxed, circular, partially double-stranded DNA molecule. There are 6 HBV genotypes: A through F.
HEPATITIS B VIRUS CLINICAL MANIFESTATIONS
HBV infection may be symptomatic or asymptomatic, though more likely to be symptomatic in young children. More than 95% of HBV infections in adults are self-limiting; the virus is cleared about 6 months post-infection and the patient is immune to reinfection. Symptoms of acute infection can include jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting, and joint pain.
Hepatitis B is transmitted by direct contact with the blood or body fluids of an infected person; e.g. having sex or sharing needles with an infected person. Infants can be infected as they pass through the birth canal of an infected mother, where they are exposed to large amounts of the virus. Hepatitis B is not spread through food, water, or by casual contact. However, the virus can be spread by sharing personal items that might have small amounts of blood present, such as toothbrushes or razors. High risk populations include people who practice unsafe sex, drug abusers, and hospital workers who have exposure to blood products.
HBV Vaccine: In 1982, a hepatitis B vaccine was made available. The number of new infections per year has declined from an average of about 260,000 in the 1980s to about 78,000 in 2001. This great decline has occurred in children and adolescents as a result of the vaccine. The HBV vaccine is now routine in the immunization schedule of infants and children.
Chronic HBV Infections: About 5% of adults will not resolve the infection and go on to become a chronic carrier. Conversely, chronic infections occur in 90% of infants infected at birth, 30% if infected at age 1 to 5 years and 6% if infected after age 5. Chronic infection is more common in infants due to their poorly developed cellular immune response. There are an estimated 1.25 million chronically infected Americans of whom 20 to 30% acquired their infection in childhood.
The clinical course of individuals who are chronically infected is highly variable, ranging from asymptomatic to a small subset with severe chronic active hepatitis, who have a 5 year survival rate of less than 50%. The reasons that some develop a chronic infection remain poorly understood. Evidence suggests that variation in host immune response is a critical factor. Individuals with overt deficits in cell-mediated immunity, such as transplant patients and HIV patients, are more likely to become chronic carriers than those with a fully competent immune response.
About 30% of chronic carriers will have no signs or symptoms. The asymptomatic carriers are the primary reservoir of infection; it is from these individuals that the spread of HBV to susceptible hosts occurs. Adults are more likely than children to be symptomatic. Symptoms can include jaundice, fatigue, abdominal pain, loss of appetite, nausea, vomiting, and joint pain. Some patients will remain in generally good health but have persistent or recurrent elevations in liver enzymes (AST/ALT) without jaundice. Persistent mild hepatomegaly is not unusual, and splenomegaly is occasionally present. Unfortunately, a significant number of chronically-infected individuals will develop cirrhosis, hepatic failure, or hepatocellular carcinoma.
Just a decade ago, HBV infection was considered a contraindication to liver transplant because of frequent viral recurrences and the development of associated liver disease, which led to graft failure and death. Antiviral therapies have diminished the risk of HBV recurrence and led to improvements in patient and graft survival. HBV infection after a liver transplant can be classified into 2 groups; patients who have HBV recurrence who were transplanted because of HBV end-stage liver disease and patients who develop HBV after the transplant from their donors or from a community acquired infection.
HEPATITIS B VIRUS LABORATORY DIAGNOSIS
HBV infection can be diagnosed and monitored with a number of antibody and antigen assays. There are a wide variety of laboratory assays available to differentiate acute from chronic infection, to assess the immune status of an individual, or to evaluate infectivity and prognosis. There are a number of excellent reviews in the primary literature to assist in understanding the immune response to HBV.
Due to the highly sensitive and specific nature of quantitative, real-time polymerase chain reaction (PCR), it has become the standard of care for assessment of viral burden (viral load) in a patient undergoing treatment for HBV. HBV often achieves titers of greater than 10e9 IU/ml; for this reason, it is important that the quantitative, real-time PCR assay employed to follow the patient has an extremely wide assay range. The ViraCor HBV assay has a range of 5 to 200,000,000 IU/ml.
HEPATITIS B VIRUS TREATMENT
Treatment of hepatitis B has evolved from isolation and bed rest in the 1950s to development of antiviral therapies in the 1990s. The ideal goal of treatment is to eradicate HBV, but this may not be achievable. The indications for treatment include evidence of viral replication and abnormal ALT levels. Patient age, severity of liver disease, likelihood of response, and the potential for adverse events must be weighed before treatment is initiated. There are a variety of treatment options available for HBV chronic infections, with the understanding of treatment rapidly evolving at this time. For an excellent review of treatment options, the Hepatitis B Foundation website is recommended: http://www.hepb.org/treatment/aasld_guidelines.htm .
Selected References
Centers for Disease Control and Prevention. http://www.cdc.gov
Hepatitis B Foundation. http://www.hepb.org
Knipe D, Howley P. Fields Virology. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.
PAO-05-0707 PCR tests are performed pursuant to a license agreement with Roche Molecular Systems, Inc.
