The genetics underlying severe COVID-19: The immune system is complex and involves many genes, including those that encode cytokines known as interferons (IFNs). Individuals that lack specific IFNs can be more susceptible to infectious diseases. Furthermore, the autoantibody system dampens IFN response to prevent damage from pathogen-induced inflammation. Two studies now examine the likelihood that genetics affects the risk of severe coronavirus disease 2019 (COVID-19) through components of this system (see the Perspective by Beck and Aksentijevich). Q. Zhang et al. used a candidate gene approach and identified patients with severe COVID-19 who have mutations in genes involved in the regulation of type I and III IFN immunity. They found enrichment of these genes in patients and conclude that genetics may determine the clinical course of the infection. Bastard et al. identified individuals with high titers of neutralizing autoantibodies against type I IFN-α2 and IFN-ω in about 10% of patients with severe COVID-19 pneumonia. These autoantibodies were not found either in infected people who were asymptomatic or had milder phenotype or in healthy individuals. Together, these studies identify a means by which individuals at highest risk of life-threatening COVID-19 can be identified. Science , this issue p. eabd4570 , p. eabd4585 ; see also p. 404

The genetics underlying severe COVID-19: The immune system is complex and involves many genes, including those that encode cytokines known as interferons (IFNs). Individuals that lack specific IFNs can be more susceptible to infectious diseases. Furthermore, the autoantibody system dampens IFN response to prevent damage from pathogen-induced inflammation. Two studies now examine the likelihood that genetics affects the risk of severe coronavirus disease 2019 (COVID-19) through components of this system (see the Perspective by Beck and Aksentijevich). Q. Zhang et al. used a candidate gene approach and identified patients with severe COVID-19 who have mutations in genes involved in the regulation of type I and III IFN immunity. They found enrichment of these genes in patients and conclude that genetics may determine the clinical course of the infection. Bastard et al. identified individuals with high titers of neutralizing autoantibodies against type I IFN-α2 and IFN-ω in about 10% of patients with severe COVID-19 pneumonia. These autoantibodies were not found either in infected people who were asymptomatic or had milder phenotype or in healthy individuals. Together, these studies identify a means by which individuals at highest risk of life-threatening COVID-19 can be identified. Science , this issue p. eabd4570 , p. eabd4585 ; see also p. 404

High‐dose methotrexate (HD‐MTX) infusions are commonly used to consolidate remission in children with acute lymphoblastic leukemia (ALL). We investigate the potential role of candidate polymorphisms in SLCO1B1 (rs4149056 and rs2306283), ABCB1 (rs1045642), ABCC2 (rs717620), ABCC3 (rs9895420), and ABCC4 (rs7317112) drug transporters genes on HD‐MTX pharmacokinetics and patients' outcome (meant both as relapse and drug‐related toxicities) in an Italian cohort of 204 ALL pediatric patients treated according to the AIEOP‐BFM ALL 2009 protocol. TaqMan SNP genotyping assays determined patient's genotypes. Measurements of HD‐MTX plasma concentration were available for 814 HD‐MTX courses in 204 patients; MTX clearance was estimated by a two‐compartmental linear pharmacokinetic model with first‐order elimination and a Bayesian approach, via ADAPT. Independent contributions of age and ABCC4 SNP rs7317112 (A>G, intronic) on MTX clearance were detected in a multivariate analysis (p = 1.57 × 10⁻⁸ and p = 2.06 × 10⁻⁵, respectively), suggesting a delayed elimination of the drug in older patients and an accelerated one in carriers of the variant GG genotype. After multiple corrections, the association between ABCC2 SNP rs717620 (−24 C>T) and severe hematological toxicity was found (p < 0.005). Moreover, SLCO1B1 SNP rs4149056 (c.521T>C, p.V174A) affected patients' outcomes: carriers of the variant C allele presented a reduced risk of relapse compared to wild‐type TT (hazard risk: 0.27, 95% confidence interval [CI]: 0.08–0.90, p = 0.037). Taken together, these data highlighted the importance of variants in drug transporters genes on HD‐MTX disposition in the AIEOP‐BFM ALL 2009 protocol consolidation phase, and their putative role as predictive markers of outcome.