High Predictivity of IL28B Genotype for Natural Clearance of HCV-RNA in Patients with Hemoglobinopathies

Patients with transfusion-dependent hemoglobinopathies, as thalassemia major (TM) and sickle/β-thalassemia (S/βThal), have an high risk to be infected by hepatitis C virus (HCV), developing chronic hepatitis C (CHC).

Current standard-of-care therapy for CHC consists of pegylated interferon-α 2 and ribavirin (PEG-IFN- α/RBV). A genome-wide association study (GWAs) identified a single nucleotide polymorphism (SNP), on chromosome 19, 3 kilobases (kb) upstream of the IL28B gene (IL28B -3kb C>T). This SNP is associated to the natural clearance of HCV-RNA. The IL28B -3kb C>T SNP is in strong linkage disequilibrium with a non-synonymous variant in the exon2 of IL28B gene (213A>G, K70R). Because of in these patients the PEG-IFN-α/RBV treatment of chronic HCV infection could be complicated by severe side adverse events, i.e. ribavirin-associated hemolysis, it is noteworthy to predict the spontaneous C virus clearance by investigate these two IL28B DNA variants. Therefore, in a cohort of 42 patients with hemoglobinopathies, it was analyzed the two mentioned DNA variants to evaluate their allele frequencies and to eventually correlate them to the C virus clearance.

Forty two patients with hemoglobinopathies, not-treated with PEG- IFN-α/RBV, were included in this study. Molecular analysi:. Genomic DNAs were extracted from peripheral blood mononuclear cells. DNA variants, IL28B -3kb C>T e K70R, were investigated by direct genomic sequencing (CEQ880-Beckman), endonuclease digestion and reverse dot-blot hybridization. PCR primers, specific for the investigated DNA regions, were designed in our laboratory on the basis of IL28B gene map (GENATLAS) and FASTA SNP sequences. According to literature, the genotype IL28B -3kbCC/K70RAA was considered most frequently associated with the spontaneous HCV-RNA clearance, whereas the genotypes IL28B 3kbTT/K70R GG and -3kbCT/K70R AG were considered most frequently associated with a persistent infection.

Allele frequencies of -3kbC>T polymorphism were 63,1% for the favourable C allele and 36,9% for the T allele. Allele frequencies for the K70R variant were 63.1% for the A allele and 36,9% for the G allele. Twenty of 42 studied patients (47,6%) showed a spontaneous HCV-RNA clearance: 15/20 (75%) had IL28B genotype -3kbCC/K70R AA, 5/20 (25%) had IL28B genotype -3kbCT/K70R AG. Twenty two of 42 studied patients (52,4%) showed HCV-RNA persistence: 13/22 (59,1%) showed viral genotype 1b and IL28B genotype -3kbCT/K70R AG; 4/22 (18,2%) showed viral genotype 1b and IL28B genotype -3kbCC/K70R AA; 4/22 (18,2%) showed IL28B genotype -3kbTT/K70R GG (3 had viral genotype 2a2c and one viral genotype 1b; one case had viral genotype 2a2c and was homozygous for the favourable -3kb C allele but it was heterozygous for the K70R mutation (Table 1).

It seems that IL28B genotype has a marked impact on natural clearance of HCV-RNA: 15/20 (75%) not treated patients who showed a spontaneous HCV-RNA clearance had an IL28B genotype promoting the viral defence (IL28B-3kbCC/K70R AA) (Table 1). These data are in agreement with Thomas et al (Thomas et al. Nature 461,798-801-2009) who showed a -3kb CC genotype in the 60% of patients who clear HCV.

Therefore, they may suggest that waiting and watch approach should be advised in patients with hemoglobinopathy and favourable IL28B genotype.

No relevant conflicts of interest to declare.