Impact of genetic ancestry on the distribution of interferon-λ4 rs12979860 polymorphism in a global population of Buenos Aires, Argentina / Impacto de la ancestría genética en la distribución del polimorfismo de interferón-λ4 rs12979860 en una población global de Buenos Aires, Argentina

ABSTRACT Human interferon-λ4 is a cytokine involved in early stages of antiviral responses. Strikingly, some allelic variants with diminished antiviral activity reduce the susceptibility to viral infections, thus they would have suffered a positive selection pressure throughout the evolutionary history of the genus Homo. An intronic variant within the IFNλ4 locus (rs12979860, T˃C) emerged as one of the main gene determinants of the response to HCV and other viruses. The rs12979860-C allele has a differential frequency in African, European and Native American populations, though South American data are scarce. Here we characterize for the first time the distribution of rs12979860 genotypes in a sample of the global population of Buenos Aires, Argentina, assessing its association with European, Native American and African parental components. The rs12979860 genotypes were determined by PCR-RFLP in DNA samples from donors of a blood banks of Buenos Aires (n=96), whose genetic individual ancestry (European, African or Native American) had been previously determined using molecular markers. The distribution of rs12979860-CC, CT and TT was 29.17%, 50.0% and 20.83%, respectively. A significant increase in the frequency of CC among donors with a strong European contribution and a greater impact of the Native American component among donors carrying the T allele were observed. Native American and European components were associated to the rs12979860 distribution in a sample of the global population of Buenos Aires, while no differences were directly attributable to the African ancestry. Considering interferon´s key role in antiviral responses, our results may contribute to both bioanthropological and immunogenetic studies associated with infectious diseases.

RESUMEN El interferón-λ4 humano es una citoquina involucrada en la respuesta antiviral. Algunas variantes alélicas con menor actividad antiviral, paradójicamente, reducen la susceptibilidad a infecciones virales, por lo que habrían sufrido una presión de selección positiva en la historia evolutiva del gיnero Homo. Una variante dentro del locus de IFNλ4 (rs12979860, T˃C), con distribución diferencial en poblaciones africanas, europeas y nativas americanas, surgió como uno de los principales determinantes genéticos de la respuesta al HCV y otros virus. Aquí caracterizamos por primera vez la distribución de los genotipos de rs12979860 en una muestra de la población cosmopolita de Buenos Aires, Argentina, evaluando el impacto de su ancesrtría. Se determinaron diferentes genotipos de rs12979860 por PCR-RFLP en muestras de ADN de donantes de bancos de sangre de Buenos Aires (n=96), cuya ancestría individual había sido previamente determinada mediante diferentes marcadores moleculares. La distribución global de rs12979860-CC, CT y TT fue 29,17%; 50,0% y 20,83%, respectivamente. Se observó un aumento significativo de la frecuencia del genotipo CC entre individuos con fuerte aporte europeo y un mayor impacto del componente nativo-americano entre portadores del alelo T. Los componentes nativo-americano y europeo se asociaron a la distribución rs12979860 en una muestra poblacional global de Buenos Aires, mientras que no se vieron diferencias directamente asociadas a la ancestría africana. Considerando el papel clave del interferón en la respuesta antiviral, nuestros resultados pueden contribuir a estudios con un enfoque bioantropológico así como a estudios inmunogenéticos asociados a enfermedades infecciosas.

Association between the IL28B rs12979860 POLYMORPHISM and therapy response in patients infected with genotype 1 of hepatitis c virus in central Brazil

Single nucleotide polymorphisms (SNPs) upstream of the IL28B gene have been associated with the spontaneous clearance of hepatitis C virus (HCV) and with a sustained virological response (SVR) to HCV infection treatment. This study aimed to investigate the association between IL28B SNP rs12979860 and SVR in patients with hepatitis C in Central Brazil. A total of 101 HCV genotype 1 mono-infected chronic patients treated with pegylated interferon and ribavirin (PEG-IFN/RBV) were studied in the City of Goiânia, Central Brazil. Analysis of rs12979860 showed that the most prevalent genotype was CT (57.4%), followed by CC (23.8%) and TT (18.8%). An overall SVR rate of 28.7% (95% CI: 20.4-38.7) was found in the study population. In a multivariate analysis, only IL28B rs12979860 CC genotype (OR: 3.77; 95% CI: 1.13-12.60; p = 0.031) was associated with SVR. These findings show that IL28B SNP rs12979860 is a strong predictor of SVR in the PEG-IFN/RBV treatment in patients infected with genotype 1 of HCV in Central Brazil

A single nucleotide polymorphism, rs129679860, in the IL28B locus is associated with the viral kinetics and a sustained virological response in a chronic, monoinfected hepatitis C virus genotype-1 Brazilian population treated with pegylated interferon-ribavirin

Single nucleotide polymorphisms (SNPs) in the interleukin (IL)28B locus have been associated with a sustained virological response (SVR) in interferon-ribavirin (IFN-RBV)-treated chronic hepatitis C virus (HCV)-infected patients in European and African populations. In this study, the genotype frequency of two IL28B SNPs (rs129679860 and rs8099917) in a cohort of chronic HCV-monoinfected patients in Brazil was evaluated and the SNP sufficient to predict the treatment response outcome was determined. A total of 66 naïve genotype-1 chronic HCV-infected patients were genotyped and the associated viral kinetics and SVR were assessed. The overall SVR was 38%. Both the viral kinetics and SVR were associated with rs129679860 genotypes (CC = 62% vs. CT = 33% vs. TT = 18%, p = 0.016). However, rs8099917 genotypes were only associated with SVR (TT = 53% vs. TG = 33% vs. GG = 18%; p = 0.032). In this population, the analysis of a single SNP, rs12979860, successfully predicts SVR in the IFN-RBV treatment of HCV.