Comprehensive assessment of miniature CRISPR-Cas12f nucleases for gene disruption.

Because of their small size, the recently developed CRISPR-Cas12f nucleases can be effectively packaged into adeno-associated viruses for gene therapy. However, a systematic evaluation of the editing outcomes of CRISPR-Cas12f is lacking. In this study, we apply a high-throughput sequencing method to comprehensively assess the editing efficiency, specificity, and safety of four Cas12f proteins in parallel with that of Cas9 and two Cas12a proteins at multiple genomic sites. Cas12f nucleases achieve robust cleavage at most of the tested sites and mainly produce deletional fragments. In contrast, Cas9 and Cas12a show relatively higher editing efficiency at the vast majority of the tested sites. However, the off-target hotspots identified in the Cas9- and Cas12a-edited cells are negligibly detected in the Cas12f-edited cells. Moreover, compared to Cas9 and Cas12a nucleases, Cas12f nucleases reduce the levels of chromosomal translocations, large deletions, and integrated vectors by 2- to 3-fold. Therefore, our findings confirm the editing capacity of Cas12f and reveal the ability of this nuclease family to preserve genome integrity during genome editing.

In-depth assessment of the PAM compatibility and editing activities of Cas9 variants.

A series of Cas9 variants have been developed to improve the editing fidelity or targeting range of CRISPR-Cas9. Here, we employ a high-throughput sequencing approach primer-extension-mediated sequencing to analyze the editing efficiency, specificity and protospacer adjacent motif (PAM) compatibility of a dozen of SpCas9 variants at multiple target sites in depth, and our findings validate the high fidelity or broad editing range of these SpCas9 variants. With regard to the PAM-flexible SpCas9 variants, we detect significantly increased levels of off-target activity and propose a trade-off between targeting range and editing specificity for them, especially for the near-PAM-less SpRY. Moreover, we use a deep learning model to verify the consistency and predictability of SpRY off-target sites. Furthermore, we combine high-fidelity SpCas9 variants with SpRY to generate three new SpCas9 variants with both high fidelity and broad editing range. Finally, we also find that the existing SpCas9 variants are not effective in suppressing genome instability elicited by CRISPR-Cas9 editing, raising an urgent issue to be addressed.

Multimorbidity in Hospitalized Patients Admitted to General Practice Departments and Its Implications for the General Practice Healthcare System: A Four-Year Longitudinal Study in China.

Objective: China and many developing countries has placed high expectations on the general practice healthcare system in terms of lowering medical costs and improving the health status of the multimorbid population in recent years. However, the prevalence of multimorbidity among inpatients attending the general practice department of hospitals and its policy implications are largely unknown. The current study aimed to analyze the prevalence of comorbidities among inpatients attending the general practice department of the tertiary Grade-A Hospitals in China, and put forward evidence-based policy recommendations. Methods: Between December 2016 and November 2020, 351 registered general practitioners from 27 tertiary hospitals were selected, and their direct admissions were evaluated. The rate and composition ratio were used for descriptive analysis of the clinical and epidemiological characteristics of multimorbidity. A backward stepwise algorithm was used to explore independent variables. The absence of multicollinearity and plausible interactions among variables were tested to ensure the robustness of the logistic regression model. The pyramid diagram was used to show the link between gender and the involved human body system in multimorbidity. Results: Multimorbidity was present in 93.1% of the 64, 395 patients who were admitted directly. Multimorbidity was significantly more prevalent in patients aged 45-59 years (OR=3.018, 95% CI=1.945-4.683), 60-74 years (OR = 4.349, 95% CI = 2.574-7.349), ≥75 years (OR = 7.804, 95% CI = 3.665-16.616), and those with body mass index (BMI) ≥ 28 kg/m2 (OR = 3.770, 95% CI = 1.453-9.785). The circulatory system was found to be the most commonly involved human body system in multimorbidity, accounting for 79.2% (95% CI = 78.8-79.5%) of all cases. Significant gender inequity was further observed in the involved human body system in multimorbidity. Conclusion: Multimorbidity is likely common among the inpatients attending the general practice department of hospitals in China and many developing countries, with significant gender inequity in the involved human body systems. Effective countermeasures include establishing a GP-PCIC multimorbidity prevention and control model and enhancing the multimorbidity of elderly and obese patients at both the clinical and healthy lifestyle levels. The diagnosis and treatment capabilities of GPs on the circulatory, endocrine, metabolic, digestive, and respiratory systems should be prioritized.