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Experiments in model organisms report abundant genetic interactions underlying biologically important traits, whereas quantitative genetics theory predicts, and data support, the notion that most genetic variance in populations is additive. Here we describe networks of capacitating genetic interactions that contribute to quantitative trait variation in a large yeast intercross population. The additive variance explained by individual loci in a network is highly dependent on the allele frequencies of the interacting loci. Modeling of phenotypes for multilocus genotype classes in the epistatic networks is often improved by accounting for the interactions. We discuss the implications of these results for attempts to dissect genetic architectures and to predict individual phenotypes and long-term responses to selection.

Using data from the German Hepatitis C-Registry (Deutsche Hepatitis C-Register, DHC-R), we report the real-world safety and effectiveness of glecaprevir/pibrentasvir (GLE/PIB) treatment and its impact on patient-reported outcomes (PROs) in underserved populations who are not typically included in clinical trials, yet who will be crucial for achieving hepatitis C virus (HCV) elimination. The DHC-R is an ongoing, non-interventional, multicenter, prospective, observational cohort study on patients treated for chronic HCV infection in Germany. The data cutoff was 17 January 2021. The primary effectiveness endpoint was sustained virologic response at post-treatment Week 12 (SVR12). Safety outcomes were assessed in all patients receiving GLE/PIB. PROs were assessed using the SF-36 survey. Of 2354 patients, 1964 had valid SVR12 data (intention-to-treat analysis). Of these, 1905 (97.0%) achieved SVR12 with rates similar across the comorbidities analyzed, except for people who actively use drugs (PWUD (active)) (86.4%). Excluding those who discontinued treatment and did not achieve SVR12, or were reinfected with HCV, the rate was 99.3%, with similar results regardless of comorbidity. PWUD (active) and those with psychiatric disorders had the most meaningful improvements in PROs. Adverse events (AEs) occurred in 631/2354 patients (26.8%), and serious AEs in 44 patients (1.9%). GLE/PIB was highly effective and well tolerated in this real-world study of patient groups key to HCV elimination.

Chronic hepatitis C can be treated very effectively with direct-acting antivirals (DAA) with only minor side effects compared to an interferon-containing treatment regimen. The significance of metabolic comorbidities after HCV cure is not well defined. This study aims to investigate short- and long-term weight change of patients receiving interferon-free antiviral treatment for chronic hepatitis C. The German Hepatitis C-registry (DHC-R) is a national multicenter real-world cohort. A total of 5111 patients were followed prospectively after DAA treatment for up to 3 years. Weight change compared to baseline was analyzed at end of treatment and at years 1, 2, and 3 after completion of antiviral therapy. Regression analysis was performed to identify baseline predictors for weight change. While there was no relevant mean weight change (-0.2 kg, SD 4.3 kg) at the end of antiviral treatment, weight started to increase during long-term follow-up reaching +1.7 kg (SD 8.0 kg, p < 0.001) compared to baseline at 3 years (follow-up year 3, FU3) after completion of antiviral therapy. 48%, 31%, and 22% of patients had a weight gain greater than 1, 3, and 5 kg at FU3, respectively. During follow-up, a body mass index (BMI) <30 proved to be the only consistent predictor for weight gain. DAA treatment is followed by a substantial weight gain (+3 kg or more) in one-third of the patients during long-term follow-up. Non-obese patients seemed to be most vulnerable to weight gain. The body compartment involved in weight gain as well as the mechanism of weight gain remain to be elucidated.

Background: Twelve weeks of the pangenotypic direct-acting antiviral (DAA) combination sofosbuvir/velpatasvir (SOF/VEL) was highly efficient in patients with hepatitis C virus (HCV) genotype 3 (GT3) infection in the ASTRAL-3 approval study. However, presence of resistance-associated substitutions (RASs) in the HCV nonstructural protein 5A (NS5A) was associated with lower treatment response., Aim: To assess the efficacy and safety of SOF/VEL ± ribavirin (RBV) and the impact of NS5A RASs and RBV use on treatment outcome in HCV GT3 infection in a real-world setting., Methods: In this multicentre cohort study, GT3 patients from ten treatment centres across Germany were included. Sustained virological response was assessed 12 weeks after end-of-treatment (SVR12) in modified intention-to-treat (mITT) and per-protocol analysis (PP). NS5A RASs were tested by population-based sequencing., Results: A total of 293 GT3 patients were included. The median age was 48 years, 70% were male, 25.3% were cirrhotic, 9.2% were HCV/HIV co-infected and 21.8% were treatment-experienced, including 4.1% with DAA experience. Baseline NS5A RASs (Y93H, A30K, L31M) were detected in 11.2%. RBV was added in 5% of noncirrhotic and 58.9% of cirrhotic patients, respectively. SVR12 rates for SOF/VEL±RBV were 95.9% (mITT) and 99.5% (PP), respectively. Only 1 virological relapse occurred in a cirrhotic patient previously treated with SOF/RBV. No treatment-related major adverse events occurred., Conclusion: Twelve weeks of SOL/VEL±RBV was safe and highly efficient in HCV GT3 across a diverse patient population. Baseline NS5A RASs were rarely observed and presence did not seem to impact SVR, regardless of the use of RBV., (© 2018 John Wiley & Sons Ltd.)