The IL28B genotype test
A new development for hepatitis C treatment is the availability of a genetic test which predicts treatment success the Il28B test now used in New Zealand and can help clinicians and patients make informed decisions on how to best manage their HCV infection.
Researchers found the gene by scanning the human genome to look for differences between people who responded well and those who did not respond to hepatitis C treatment.
Because people inherit one copy of a gene from each parent, and may get either the high-risk or the protective variation, they can end up with one of three different genotypes: two copies of the high-risk variant, two copies of the protective variant or one of each.
The Il28B test results are expressed as allele combinations, C/C, C/T, or TT
The IL28B genotype test can be used to predict response to peg-IFN and RBV in HCV genotype 1 patients. The test result indicates whether the patient has an IL28B CC, CT, or TT genotype. Patients who have the IL28B CC genotype are more likely to have a SVR with peg-IFN and RBV treatment, whereas patients who have the TT genotype are more likely to be non responders. This information can help clinicians and patients make informed decisions on how to best manage their HCV infection.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3024597/
Among treatment naive Genotype 1-infected subjects of European ancestry who were enrolled in the IDEAL study, approximately 69% of those who carried 2 C alleles (C/C) at rs12979860 achieved an SVR compared with 33% of those with the C/T genotype and 27% with genotype T/T.[7]
http://www.medscape.com/viewarticle/740029
Direct-acting antiviral agents (DAAs) and The IL28B genotype test
The availability of IL28B genotype testing to help predict SVR coincides with another major advance in the treatment of chronic hepatitis C, the introduction of direct-acting antiviral agents (DAAs) that specifically target enzymes critical to HCV replication
data suggest that carriers of the less favourable IL28B genotypes will be less likely to respond to triple therapy that includes protease inhibitors and raise the possibility that IL28B genotype-based models may be useful for predicting the likelihood of SVR in response to treatment with peginterferon + ribavirin + protease inhibitors.
http://www.medscape.com/viewarticle/740029
Strikingly, Dr Rauch said, all the teams found an association between favourable treatment response and single nucleotide polymorphisms (SNPs) in the IL28 gene near the “B” subunit that encodes interferon lambda-3. This finding was “very consistent” among four studies published over the past six months, all looking at HIV-negative individuals.
Each research group identified several relevant SNPs, but one – known as rs8099917 or the “risk allele” – was common to all of them; another, rs12980275, was identified in three studies.
Across the studies, the high-risk genotype was approximately half as common amongst people who achieved sustained virological response to interferon-based therapy than amongst non-responders. It was even rarer amongst people who spontaneously cleared HCV without treatment.
Thoughtful incorporation of IL28B genotyping into treatment decision-making may serve to increase the number of patients for whom treatment is successful while minimizing those in whom it is deleterious.
http://hepatitiscnewdrugs.blogspot.co.nz/2011/04/hepatitis-c-il28b-genotype-testing-now.html
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