Nature Medicine最新文献

Deaths of parents and grandparent caregivers threaten child well-being owing to losses of care, financial support, safety and family stability, but are relatively unrecognized as a public health crisis. Here we used cause-specific vital statistics death registrations in a modeling approach to estimate the full magnitude of orphanhood incidence and prevalence among US children aged 0–17 years between 2000 and 2021 by cause, child age, race and ethnicity, sex of deceased parent and state, and also accounted for grandparent caregiver loss using population survey data. In 2021, we estimate that 2.91 million children (4.2% of children) had in their lifetime experienced prevalent orphanhood and caregiver death combined, with incidence increasing by 49.5% and prevalence by 7.9% since 2000. Populations disproportionately affected by orphanhood included 5.2% of all adolescents; 6.4% and 4.7%, respectively, of non-Hispanic American Indian or Alaska Native, and non-Hispanic Black children; and children in southern and eastern states. In 2021, drug overdose was the leading cause of orphanhood among non-Hispanic white children, but not among minoritized subgroups. Effective policies and programs to support nearly three million bereaved children are needed to reduce the acute and long-term negative effects of orphanhood.

Respiratory syncytial virus (RSV) causes a substantial health burden among infants and older adults. Prefusion F protein-based vaccines have shown high efficacy against RSV disease in clinical trials, offering promise for mitigating this burden through maternal and older adult immunization. Employing an individual-based model, we evaluated the impact of RSV vaccination on hospitalizations and deaths in 13 high-income countries, assuming that the vaccine does not prevent infection or transmission. Using country-specific vaccine uptake rates for seasonal influenza, we found that vaccination of older adults would prevent hospitalizations by a median of 35–64% across the countries studied here. Vaccination of pregnant women could avert infant hospitalizations by 5–50%. Reductions in RSV-related mortality mirrored those estimated for hospitalizations. While substantial hospitalization costs could be averted, the impact of vaccination depends critically on uptake rates. Enhancing uptake and accessibility is crucial for maximizing the real-world impact of vaccination on reducing RSV burden among vulnerable populations.

Premarital genomic screening can help curb the burden of rare recessive disorders in populations with high rates of consanguineous marriages. Arab populations of the Middle East have a unique genetic blend characterized by founder mutations due to historical bottlenecks, and diverse allelic series shaped by a long history of migrations and intermixing. The risk of homozygous pathogenic variants, which can lead to recessive genetic disorders, is elevated because of the high prevalence of consanguineous marriages, particularly unions between first cousins, culturally rooted in this region¹. As a result, the cumulative incidence of rare recessive disorders is expected to be higher in Arab populations compared to others, often leading to chronic, severe and life-limiting conditions, such as hemoglobinopathies, spinal muscular atrophy, congenital malformations and metabolic disorders². This places an immense emotional and financial strain on affected families and healthcare systems across the region.

Premarital genomic screening presents a promising solution to mitigate this growing burden. By identifying carrier couples before marriage (particularly those who may unknowingly harbor the same deleterious variants), this approach provides critical information that enables informed reproductive decisions and could substantially reduce the incidence of genetic disorders and their associated burden across the region. Couples identified as carriers can seek genetic counseling to understand the implications of their results and to explore a range of options, including in vitro fertilization and pre-implantation genetic diagnosis or alternative family planning strategies. Regions that have successfully implemented screening programs have seen a marked decline in the incidence of recessive genetic conditions, further demonstrating their efficacy^3,4,5. Growing evidence from the region suggests that carrier screening offers a cost-effective preventive strategy relative to postnatal treatment or other management alternatives⁶.

Following our previous experience with cardiac xenotransplantation of a genetically modified porcine heart into a live human, we sought to achieve improved results by selecting a healthier recipient and through more sensitive donor screening for potential zoonotic pathogens. Here we transplanted a 10-gene-edited pig heart into a 58-year-old man with progressive, debilitating inotrope-dependent heart failure due to ischemic cardiomyopathy who was not a candidate for standard advanced heart failure therapies. He was maintained on a costimulation (anti-CD40L, Tegoprubart) blockade-based immunomodulatory regimen. The xenograft initially functioned well, with excellent systolic and diastolic function during the first several weeks posttransplantation. Subsequently, the xenograft developed rapidly progressing diastolic heart failure, biventricular wall thickening and, ultimately, near-complete loss of systolic function necessitating initiation of extracorporeal membranous oxygenation on day 31. Given these setbacks, the patient chose to transition to comfort care after 40 days. As with our first patient, histology did not reveal substantial immune cell infiltration but suggested capillary endothelial injury with interstitial edema and early fibrosis. No evidence of porcine cytomegalovirus replication in the xenograft was observed. Strategies to overcome the obstacle of antibody-mediated rejection are needed to advance the field of xenotransplantation.

The adoption of large language models (LLMs) in healthcare demands a careful analysis of their potential to spread false medical knowledge. Because LLMs ingest massive volumes of data from the open Internet during training, they are potentially exposed to unverified medical knowledge that may include deliberately planted misinformation. Here, we perform a threat assessment that simulates a data-poisoning attack against The Pile, a popular dataset used for LLM development. We find that replacement of just 0.001% of training tokens with medical misinformation results in harmful models more likely to propagate medical errors. Furthermore, we discover that corrupted models match the performance of their corruption-free counterparts on open-source benchmarks routinely used to evaluate medical LLMs. Using biomedical knowledge graphs to screen medical LLM outputs, we propose a harm mitigation strategy that captures 91.9% of harmful content (F1 = 85.7%). Our algorithm provides a unique method to validate stochastically generated LLM outputs against hard-coded relationships in knowledge graphs. In view of current calls for improved data provenance and transparent LLM development, we hope to raise awareness of emergent risks from LLMs trained indiscriminately on web-scraped data, particularly in healthcare where misinformation can potentially compromise patient safety.

Large language models (LLMs) have shown promise in medical question answering, with Med-PaLM being the first to exceed a ‘passing’ score in United States Medical Licensing Examination style questions. However, challenges remain in long-form medical question answering and handling real-world workflows. Here, we present Med-PaLM 2, which bridges these gaps with a combination of base LLM improvements, medical domain fine-tuning and new strategies for improving reasoning and grounding through ensemble refinement and chain of retrieval. Med-PaLM 2 scores up to 86.5% on the MedQA dataset, improving upon Med-PaLM by over 19%, and demonstrates dramatic performance increases across MedMCQA, PubMedQA and MMLU clinical topics datasets. Our detailed human evaluations framework shows that physicians prefer Med-PaLM 2 answers to those from other physicians on eight of nine clinical axes. Med-PaLM 2 also demonstrates significant improvements over its predecessor across all evaluation metrics, particularly on new adversarial datasets designed to probe LLM limitations (P < 0.001). In a pilot study using real-world medical questions, specialists preferred Med-PaLM 2 answers to generalist physician answers 65% of the time. While specialist answers were still preferred overall, both specialists and generalists rated Med-PaLM 2 to be as safe as physician answers, demonstrating its growing potential in real-world medical applications.

Stargardt disease is a currently untreatable, inherited neurodegenerative disease that leads to macular degeneration and blindness due to loss-of-function mutations in the ABCA4 gene. We have designed a dual adeno-associated viral vector encoding a split-intein adenine base editor to correct the most common mutation in ABCA4 (c.5882G>A, p.Gly1961Glu). We optimized ABCA4 base editing in human models, including retinal organoids, induced pluripotent stem cell-derived retinal pigment epithelial (RPE) cells, as well as adult human retinal explants and RPE/choroid explants in vitro. The resulting gene therapy vectors achieved high levels of gene correction in mutation-carrying mice and in female nonhuman primates, with average editing of 75% of cones and 87% of RPE cells in vivo, which has the potential to translate to a clinical benefit. No off-target editing was detectable in human retinal explants and RPE/choroid explants. The high editing rates in primates show promise for efficient gene editing in other ocular diseases that are targetable by base editing.

Up to 50–70% of patients with liver cirrhosis develop hepatic encephalopathy (HE), which is closely related to gut microbiota dysbiosis, with an unclear mechanism. Here, by constructing gut–brain modules to assess bacterial neurotoxins from metagenomic datasets, we found that phenylalanine decarboxylase (PDC) genes, mainly from Ruminococcus gnavus, increased approximately tenfold in patients with cirrhosis and higher in patients with HE. Cirrhotic, not healthy, mice colonized with R. gnavus showed brain phenylethylamine (PEA) accumulation, along with memory impairment, symmetrical tremors and cortex-specific neuron loss, typically found in patients with HE. This accumulation of PEA was primarily driven by decreased monoamine oxidase-B activity in both the liver and serum due to cirrhosis. Targeting PDC or PEA reversed the neurological symptoms induced by R. gnavus. Furthermore, fecal microbiota transplantation from patients with HE to germ-free cirrhotic mice replicated these symptoms and further corroborated the efficacy of targeting PDC or PEA. Clinically, high baseline PEA levels were linked to a sevenfold increased risk of HE after intrahepatic portosystemic shunt procedures. Our findings expand the understanding of the gut–liver–brain axis and identify a promising therapeutic and predictive target for HE.