Genome-wide programmable transcriptional memory by CRISPR-based epigenome editing.

A general approach for heritably altering gene expression has the potential to enable many discovery and therapeutic efforts. Here, we present CRISPRoff-a programmable epigenetic memory writer consisting of a single dead Cas9 fusion protein that establishes DNA methylation and repressive histone modifications. Transient CRISPRoff expression initiates highly specific DNA methylation and gene repression that is maintained through cell division and differentiation of stem cells to neurons. Pairing CRISPRoff with genome-wide screens and analysis of chromatin marks establishes rules for heritable gene silencing. We identify single guide RNAs (sgRNAs) capable of silencing the large majority of genes including those lacking canonical CpG islands (CGIs) and reveal a wide targeting window extending beyond annotated CGIs. The broad ability of CRISPRoff to initiate heritable gene silencing even outside of CGIs expands the canonical model of methylation-based silencing and enables diverse applications including genome-wide screens, multiplexed cell engineering, enhancer silencing, and mechanistic exploration of epigenetic inheritance.

CoRAL accurately resolves extrachromosomal DNA genome structures with long-read sequencing.

Extrachromosomal DNA (ecDNA) is a central mechanism for focal oncogene amplification in cancer, occurring in approximately 15% of early-stage cancers and 30% of late-stage cancers. EcDNAs drive tumor formation, evolution, and drug resistance by dynamically modulating oncogene copy-number and rewiring gene-regulatory networks. Elucidating the genomic architecture of ecDNA amplifications is critical for understanding tumor pathology and developing more effective therapies. Paired-end short-read (Illumina) sequencing and mapping have been utilized to represent ecDNA amplifications using a breakpoint graph, where the inferred architecture of ecDNA is encoded as a cycle in the graph. Traversals of breakpoint graph have been used to successfully predict ecDNA presence in cancer samples. However, short-read technologies are intrinsically limited in the identification of breakpoints, phasing together of complex rearrangements and internal duplications, and deconvolution of cell-to-cell heterogeneity of ecDNA structures. Long-read technologies, such as from Oxford Nanopore Technologies, have the potential to improve inference as the longer reads are better at mapping structural variants and are more likely to span rearranged or duplicated regions. Here, we propose CoRAL (Complete Reconstruction of Amplifications with Long reads), for reconstructing ecDNA architectures using long-read data. CoRAL reconstructs likely cyclic architectures using quadratic programming that simultaneously optimizes parsimony of reconstruction, explained copy number, and consistency of long-read mapping. CoRAL substantially improves reconstructions in extensive simulations and 10 datasets from previously-characterized cell lines as compared to previous short and long-read based tools. As long-read usage becomes wide-spread, we anticipate that CoRAL will be a valuable tool for profiling the landscape and evolution of focal amplifications in tumors.

ecDNA hubs drive cooperative intermolecular oncogene expression.

Extrachromosomal DNA (ecDNA) is prevalent in human cancers and mediates high expression of oncogenes through gene amplification and altered gene regulation1. Gene induction typically involves cis-regulatory elements that contact and activate genes on the same chromosome2,3. Here we show that ecDNA hubs-clusters of around 10-100 ecDNAs within the nucleus-enable intermolecular enhancer-gene interactions to promote oncogene overexpression. ecDNAs that encode multiple distinct oncogenes form hubs in diverse cancer cell types and primary tumours. Each ecDNA is more likely to transcribe the oncogene when spatially clustered with additional ecDNAs. ecDNA hubs are tethered by the bromodomain and extraterminal domain (BET) protein BRD4 in a MYC-amplified colorectal cancer cell line. The BET inhibitor JQ1 disperses ecDNA hubs and preferentially inhibits ecDNA-derived-oncogene transcription. The BRD4-bound PVT1 promoter is ectopically fused to MYC and duplicated in ecDNA, receiving promiscuous enhancer input to drive potent expression of MYC. Furthermore, the PVT1 promoter on an exogenous episome suffices to mediate gene activation in trans by ecDNA hubs in a JQ1-sensitive manner. Systematic silencing of ecDNA enhancers by CRISPR interference reveals intermolecular enhancer-gene activation among multiple oncogene loci that are amplified on distinct ecDNAs. Thus, protein-tethered ecDNA hubs enable intermolecular transcriptional regulation and may serve as units of oncogene function and cooperative evolution and as potential targets for cancer therapy.

Limitations of antifungal prophylaxis in preventing invasive Candida surgical site infections after liver transplant surgery.

Invasive primary Candida surgical site infections (IP-SSIs) are a common complication of liver transplantation, and targeted antifungal prophylaxis is an efficient strategy to limit their occurrence. We performed a retrospective single-center cohort study among adult single liver transplant recipients at Duke University Hospital in the period between 1 January 2015 and 31 December 2020. The study aimed to determine the rate of Candida IP-SSI according to the peri-transplant antifungal prophylaxis received. Of 470 adult single liver transplant recipients, 53 (11.3%) received micafungin prophylaxis, 100 (21.3%) received fluconazole prophylaxis, and 317 (67.4%) did not receive systemic antifungal prophylaxis in the peri-transplant period. Ten Candida IP-SSIs occurred among 5 of 53 (9.4%) micafungin recipients, 1 of 100 (1.0%) fluconazole recipients, and 4 of 317 (1.3%) recipients who did not receive antifungal prophylaxis. Our study highlights the limitations of antifungal prophylaxis in preventing invasive Candida IP-SSI after liver transplant surgery. We hypothesize that pathogen, host, and pharmacokinetic-related factors contributed to the occurrence of Candida IP-SSI despite antifungal prophylaxis. Our study reinforces the need for a risk-based, multi-pronged approach to fungal prevention, including targeted antifungal administration in patients with risks for invasive candidiasis and close monitoring, especially among patients with surgically complex procedures, with timely control of surgical leaks.

Family poverty over the early life course and adult experiences of intimate partner violence: a cohort study.

OBJECTIVES: This study aimed to determine whether family poverty over the early childhood, adolescent, and adult periods of the life course independently predicts experiences of intimate partner violence (IPV) in adulthood. STUDY DESIGN: This was a birth cohort study in Brisbane, Australia, with pregnant women recruited at their first booking-in visit and their children, followed up to 30 and 40 years of age. METHODS: Family income was obtained from the mother when the child was 6 months, 5 and 14 years of age. Offspring reported their own family income at 21, 30, and 40 years of age. The offspring completed the Composite Abuse Scale at 30 and 40 years. Adjusted logistic regression models are used to predict experiences of IPV at 30 (n = 2157) and 40 (n = 1438) years. RESULTS: The findings at 30 and 40 years of age are consistent. Only poverty experienced concurrently with the assessment of IPV is strongly associated. At the 40-year follow-up, family poverty predicts higher ratios of all four forms of IPV; severe combined abuse (odds ratio [OR] = 2.24, 95% confidence interval [CI] = 1.24, 4.05), physical abuse (OR = 3.37, 95% CI = 1.95, 5.82), emotional abuse (OR = 2.09, 95% CI = 2.58, 8.57) and harassment (OR = 4.70, 95% CI = 2.58, 8.57). CONCLUSION: Concurrent family poverty is strongly and consistently associated with patterns of IPV. These associations are for cross-sectionally collected data with the prospectively collected data not replicating these findings. Although it is not possible to identify a specific causal pathway, the findings suggest that the immediate consequences of poverty are strongly associated with IPV. Programmes that address poverty reduction provide the best prospect for reducing societal levels of IPV.

Telehealth Use during COVID-19: An Exploratory Study on Adaptations and Experiences of Providers.

The current exploratory study examines the impact of the rapid acceleration of telehealth during the COVID-19 pandemic from the perspective of healthcare providers. Understanding provider perspectives, particularly in terms of adaptations made during this critical time, is a useful lens into service innovation in times of crisis and can help elucidate successful strategies for continuing the use of telehealth during the postpandemic period. Fourteen providers from 11 different service agencies in a southeastern state were interviewed. Findings identified three themes: (1) dynamic adaptations enacted by healthcare providers at the onset of the pandemic, such as hybrid services, rapid innovations in workflow, collective decision making among providers, and outreach to educate patients; (2) the relaxation of policies by regulators/insurers, focused most often on reimbursement of services; and (3) how patient engagement was impacted via telehealth, including openness to telehealth, more family-level accessibility, and reduced no-show rates. Implications for social workers include heightened professional training on telehealth as well as increasing the critical role that social workers serve in educating providers and patients on telehealth.

Physician's Knowledge and Practices Surrounding Low-Dose Aspirin for Preeclampsia Risk Reduction.

OBJECTIVE: Preeclampsia is a leading cause of pregnancy-related deaths. Up to 60% of maternal deaths associated with preeclampsia may be prevented. Clinical trials have shown that low-dose aspirin reduces preeclampsia up to 30% among women at increased risk. Since 2014, multiple professional societies and the U.S. Preventive Services Task Force have released guidelines on the use of low-dose aspirin to reduce the risk of preeclampsia. We aimed to evaluate physician's knowledge and practices surrounding low-dose aspirin for preeclampsia risk reduction. STUDY DESIGN: We distributed an anonymous electronic survey to licensed physicians in the Rio Grande Valley of Texas who provide prenatal care, including general obstetrician-gynecologists, maternal fetal medicine subspecialists, and family medicine physicians. The survey consisted of 20 items assessing demographics, provider practices, and knowledge on the use of low-dose aspirin for preeclampsia risk reduction. RESULTS: We received 48 surveys with a response rate of 55%. More than 90% of physicians reported recommending low-dose aspirin for preeclampsia risk reduction, of which 98% correctly identified the dose. Of the physicians recommending aspirin, 83% initiate dosing between 12 and 16 weeks, but only 52% continue it until the day of delivery. Nearly 80% of respondents identified that one high-risk factor for preeclampsia is an indication for prophylaxis, but only 56% identified that two or more moderate risk factors should prompt aspirin recommendation. CONCLUSION: Despite clear professional guidelines, physicians demonstrated gaps in knowledge and differences in practices. Enhancing screening tools to assess patient's risk of developing preeclampsia and tailored medical education on moderate risk factors are needed to identify patients who may benefit from this intervention. Increasing the use of aspirin in patients at risk is critical given the benefits of low-dose aspirin in the reduction of poor maternal and neonatal outcomes related to preeclampsia. KEY POINTS: · Low-dose aspirin reduces preeclampsia in patients up to 30%.. · Physicians have gaps in knowledge despite guidelines.. · Following guidelines reduces poor outcomes associated with preeclampsia..

Librarian and Researcher Assessments of Search Result Relevance: How Well Do They Align?

Conducting comprehensive but efficient literature searches for complex evidence syntheses involves selecting databases that will retrieve the greatest number of relevant results on the question. Lack of a comprehensive single database on allied health educational topics challenges those seeking such literature. In this study, six participants contributed research questions on instructional methods and materials for allied health patients, caregivers, and future health professionals. Two health sciences librarians created search strategies for these questions and searched eleven databases. Both the librarians and the six participants evaluated the search results using a rubric based on PICO to assess extent of alignment between the librarians' and requestors' relevance judgments. Intervention, Outcome, and Assessment Method constituted the most frequent bases for assessments of relevance by both librarians and participants. The librarians were more restrictive in all of their assessments except in a preliminary search yielding twelve citations without abstracts. The study's results could be used to identify effective techniques for reference interviewing, selecting databases, and weeding search results.

Fundamentals of osteoarthritis: outcome evaluation with patient-reported measures and functional tests.

Evaluating outcome in osteoarthritis (OA) clinical research and practice requires reliable, valid and responsive patient-reported outcome measures (PROMs) and functional tests that reflect important problems experienced by people with OA. The goal of this work is to provide information to start to guide the reader in selecting measures for people with OA. In this narrative review, we begin by providing an overview of measurement properties that can help clinicians and researchers in making decisions about whether a measure might be appropriate for use in their research or clinical context. We then report evidence supporting the use of measures of pain (e.g., Pain Visual Analogue (VAS), Numeric Pain Rating Scale (NPRS), Intermittent and Constant Osteoarthritis Pain, PROMIS Pain Interference, and, for screening in research, the painDETECT and the Self-report Leeds Assessment of Neuropathic Symptoms and Signs) and fatigue (e.g., PROMIS-Fatigue) at a group level in clinical research. Several multi-dimensional joint-specific measures (e.g., Western Ontario McMaster Universities' Osteoarthritis Outcomes Scale, Knee/Hip Injury and Osteoarthritis Outcome Score, Oxford Hip/Knee Scale) also have evidence for group-level use. Functional tests (e.g., timed walk tests, 30 Second Chair Stand, Timed Up and Go, etc.) have measurement properties supporting their use at the group level in clinical research and at the individual patient level as do the pain VAS and NPRS. Other generic and disease-specific PROMs have been used in or could be used in OA studies but their measurement properties require further evaluation in people with OA.

Development and validation of the Flare-OA questionnaire for measuring flare in knee and hip osteoarthritis.

OBJECTIVE: Ability to assess flares in osteoarthritis (OA) of the knee and hip (KHOA) is important in clinical care and research. Using mixed methods, we developed a self-reported instrument measuring flare and assessed its psychometric properties. METHODS: We constructed questionnaire items from semi-structured interviews and a focus group (patients, clinicians) by using a dual-language (English-French) approach. A Delphi consensus method was used to select the most relevant items. Patients with OA from Australia, France and the United States completed the preliminary Flare-OA, HOOS, KOOS and Mini-OAKHQOL questionnaires online. We used a factor analysis and content approach to reduce items and determine structural validity. We tested the resulting questionnaire (score 0-100) for internal consistency, convergent and known-groups validity. RESULTS: Initially, 180 statements were generated and reduced to 33 items in five domains (response 0 = not at all, to 10 = absolutely) by Delphi consensus (50 patients, 116 professionals) and an expert meeting. After 398 patients (mean [SD] age 64 [8.5] years, 70.4% female, 86.7% knee OA) completed the questionnaire, it was reduced to 19 items by factor analysis and a content approach (RMSEA = 0.06; CFI = 0.96; TLI = 0.94). The Cronbach's alpha was >0.9 for the five domains and the whole questionnaire. Correlation coefficients between Flare-OA and other instrument scores were as predicted, supporting construct validity. The difference in Flare-OA score between patients with and without flare (31.8) largely exceeded 2 SEM (10.2). CONCLUSION: Flare-OA is a valid and reliable patient-reported instrument for assessing the occurrence and severity of flare in patients with KHOA in clinical research.

TURN-IT: a novel turning intervention program to improve quality of turning in daily life in people with Parkinson's disease.

BACKGROUND: People with Parkinson's disease (PD) have a high fall rate and many falls are associated with turns. Despite this, there is minimal research on effects of rehabilitation on the quality of turns. Further, quantifying turns in the home may have broader implications since rehabilitation of turns would ideally improve turning in real world mobility. METHODS: Sixty people with PD and a history of falls will be randomized to receive either a novel TURNing InTervention (TURN-IT) or no intervention (control group). The TURN-IT group will be seen for 6 weeks (18 visits) for an individualized, progressive program that is based on the specific constraints of turning in PD. Wearable sensors will be used to measure 7 days of mobility, including turns, before and after intervention or control period. In addition, blinded assessments of gait, mobility and turns will occur before and after intervention for both groups and falls will be monitored for twelve months post intervention with bimonthly email questionnaires. DISCUSSION: This study has the potential to change how we rehabilitate and assess turning in people with PD and falls. There are several novel aspects to our study including a comprehensive turning-focused intervention that is tailored to the underlying constraints that impair turning in people with PD. Further, our outcome measure of turning quality during 7 days of daily life is novel and has implications for determining real-life changes after rehabilitation. The ultimate goal of this rehabilitation intervention is to improve how patients turn in daily life and to reduce falls. TRIALS REGISTRATION: This protocol is registered at clinicaltrials.gov; #NCT04897256; https://clinicaltrials.gov/ct2/show/NCT04897256?term=Horak&cond=Parkinson+Disease&draw=2&rank=4 .

Benefits and Challenges of Implementing Telehealth in Rural Settings: A Mixed-Methods Study of Behavioral Medicine Providers.

Social workers and other healthcare professionals face increasing pressure to expand access, efficiency, and quality of healthcare to rural patients. Telehealth has become a viable and necessary tool to address gaps in healthcare for rural areas. Unfortunately, little is known about the benefits and challenges of using these services to meet the needs of rural communities. This mixed-methods study examines telehealth implementation among healthcare organizations in a predominantly rural state. Seventeen providers from 11 organizations were interviewed. Most had used live video conferencing, and about a third used mobile technologies, but fewer providers had experience with store-and-forward or remote patient monitoring. Analyses of qualitative data collected via interviews revealed two main themes among benefits of telehealth implementation: (1) increased inter- and intra-agency coordination and (2) savings in time, travel, and efficiency. Three main themes emerged among barriers to telehealth: (1) organizational capacity, (2) patient skills and comfort, and (3) provider knowledge and skills. Recommendations are provided for social workers and other healthcare professionals related to expanding utilization of telehealth services to improve access to healthcare for rural populations.

Clinical likelihood ratios and balanced accuracy for 44 in silico tools against multiple large-scale functional assays of cancer susceptibility genes.

PURPOSE: Where multiple in silico tools are concordant, the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) framework affords supporting evidence toward pathogenicity or benignity, equivalent to a likelihood ratio of ~2. However, limited availability of "clinical truth sets" and prior use in tool training limits their utility for evaluation of tool performance. METHODS: We created a truth set of 9,436 missense variants classified as deleterious or tolerated in clinically validated high-throughput functional assays for BRCA1, BRCA2, MSH2, PTEN, and TP53 to evaluate predictive performance for 44 recommended/commonly used in silico tools. RESULTS: Over two-thirds of the tool-threshold combinations examined had specificity of <50%, thus substantially overcalling deleteriousness. REVEL scores of 0.8-1.0 had a Positive Likelihood Ratio (PLR) of 6.74 (5.24-8.82) compared to scores <0.7 and scores of 0-0.4 had a Negative Likelihood Ratio (NLR) of 34.3 (31.5-37.3) compared to scores of >0.7. For Meta-SNP, the equivalent PLR = 42.9 (14.4-406) and NLR = 19.4 (15.6-24.9). CONCLUSION: Against these clinically validated "functional truth sets," there was wide variation in the predictive performance of commonly used in silico tools. Overall, REVEL and Meta-SNP had best balanced accuracy and might potentially be used at stronger evidence weighting than current ACMG/AMP prescription, in particular for predictions of benignity.

SRD-1 in AWA neurons is the receptor for female volatile sex pheromones in C. elegans males.

Pheromones are critical cues for attracting mating partners for successful reproduction. Sexually mature Caenorhabditis remanei virgin females and self-sperm-depleted Caenorhabditis elegans hermaphrodites produce volatile sex pheromones to attract adult males of both species from afar. The chemoresponsive receptor in males has remained unknown. Here, we show that the male chemotactic behavior requires amphid sensory neurons (AWA neurons) and the G-protein-coupled receptor SRD-1. SRD-1 expression in AWA neurons is sexually dimorphic, with the levels being high in males but undetectable in hermaphrodites. Notably, srd-1 mutant males lack the chemotactic response and pheromone-induced excitation of AWA neurons, both of which can be restored in males and hermaphrodites by AWA-specific srd-1 expression, and ectopic expression of srd-1 in AWB neurons in srd-1 mutants results in a repulsive behavioral response in both sexes. Furthermore, we show that the C-terminal region of SRD-1 confers species-specific differences in the ability to perceive sex pheromones between C. elegans and C. remanei These findings offer an excellent model for dissecting how a single G-protein-coupled receptor expressed in a dimorphic neural system contributes to sex-specific behaviors in animals.

Examining the role of mother-child interactions and DNA methylation of the oxytocin receptor gene in understanding child controlling attachment behaviors.

This study examined mother-child interactions and DNA methylation of the oxytocin receptor (OXTR) gene in the child, in relation with controlling-attachment behaviors at early preschool age. Maternal interactive behaviors were coded using the Emotional Availability Scales, and child attachment behaviors were assessed with the Separation-Reunion procedure and coded with the Preschool Attachment Rating Scales. DNA methylation data were captured from exon 3 of the OXTR. Results indicated that lower maternal sensitivity was associated with more controlling-caregiving behaviors, and that less maternal structuring was associated with more controlling-punitive behaviors. Hypomethylation of the OXTR gene was associated with greater maternal structuring behaviors, and with more child controlling-caregiving behaviors. The moderating role of the OXTR gene was examined in the association between interactive behaviors and child controlling behaviors, but no interaction effect was found. These results suggest that maternal interactive behaviors and OXTR methylation are independently associated with child controlling attachment.

Magic Curiosity Arousing Tricks (MagicCATs): A novel stimulus collection to induce epistemic emotions.

There has been considerable interest in empirical research on epistemic emotions, i.e., emotions related to knowledge-generating qualities of cognitive tasks and activities such as curiosity, interest, and surprise. One big challenge when studying epistemic emotions is systematically inducting these emotions in restricted experimental settings. The current study created a novel stimulus set called Magic Curiosity Arousing Tricks (MagicCATs): a collection of 166 short magic trick video clips that aim to induce a variety of epistemic emotions. MagicCATs are freely available for research and can be used in a variety of ways to examine epistemic emotions. Rating data also support that the magic tricks elicit a variety of epistemic emotions with sufficient inter-stimulus variability, demonstrating good psychometric properties for their use in psychological experiments.

Are medical comorbidities contributing to the use of opioid analgesics in patients with knee osteoarthritis?

BACKGROUND: Although opioid analgesics are not generally recommended for treatment of knee osteoarthritis (OA), they are frequently used. We sought to determine the association between medical comorbidities and self-reported opioid analgesic use in these patients. METHODS: This cross-sectional study recruited patients referred to two provincial hip and knee clinics in Alberta, Canada for consideration of total knee arthroplasty. Standardized questionnaires assessed demographic (age, gender, income, education, social support, smoking status) and clinical (pain, function, total number of troublesome joints) characteristics, comorbid medical conditions, and non-surgical OA management participants had ever used or were currently using. Multivariable Poisson regression with robust estimate of the standard errors assessed the association between comorbid medical conditions and current opioid use, controlling for potential confounders. RESULTS: 2,127 patients were included: mean age 65.4 (SD 9.1) years and 59.2% female. Currently used treatments for knee OA were: 57.6% exercise and/or physiotherapy, 61.1% NSAIDs, and 29.8% opioid analgesics. In multivariable regression, controlling for potential confounders, comorbid hypertension (RR 1.18, 95% CI 1.02-1.37), gastrointestinal disease (RR 1.31, 95% CI 1.07-1.60), depressed mood (RR 1.25, 95% CI 1.05-1.48) and a higher number of troublesome joints (RR 1.04 per joint, 95% CI 1.00-1.09) were associated with opioid use, with no association found with having ever used recommended non-opioid pharmacological or non-pharmacological treatments. CONCLUSIONS: In a large cohort of patients with knee OA, of 12 comorbidities assessed, comorbid hypertension, gastrointestinal disease, and depressed mood were associated with current use of opioid analgesics, in addition to total burden of troublesome joints. Improved guidance on the management of painful OA in the setting of common comorbidities is warranted.

Emergency Department Management of the Covid-19 Pandemic.

BACKGROUND: Emergency departments (EDs) need to be prepared to manage crises and disasters in both the short term and the long term. The coronavirus disease 2019 (COVID-19) pandemic has necessitated a rapid overhaul of several aspects of ED operations in preparation for a sustained response. OBJECTIVE: We present the management of the COVID-19 crisis in 3 EDs (1 large academic site and 2 community sites) within the same health care system. DISCUSSION: Aspects of ED throughput, including patient screening, patient room placement, and disposition are reviewed, along with departmental communication procedures and staffing models. Visitor policies are also discussed. Special considerations are given to airway management and the care of psychiatric patients. Brief guidance around the use of personal protective equipment is also included. CONCLUSIONS: A crisis like the COVID-19 pandemic requires careful planning to facilitate urgent restructuring of many aspects of an ED. By sharing our departments' responses to the COVID-19 pandemic, we hope other departments can better prepare for this crisis and the next.

Engineering Protein-Secreting Plasma Cells by Homology-Directed Repair in Primary Human B Cells.

The ability to engineer primary human B cells to differentiate into long-lived plasma cells and secrete a de novo protein may allow the creation of novel plasma cell therapies for protein deficiency diseases and other clinical applications. We initially developed methods for efficient genome editing of primary B cells isolated from peripheral blood. By delivering CRISPR/CRISPR-associated protein 9 (Cas9) ribonucleoprotein (RNP) complexes under conditions of rapid B cell expansion, we achieved site-specific gene disruption at multiple loci in primary human B cells (with editing rates of up to 94%). We used this method to alter ex vivo plasma cell differentiation by disrupting developmental regulatory genes. Next, we co-delivered RNPs with either a single-stranded DNA oligonucleotide or adeno-associated viruses containing homologous repair templates. Using either delivery method, we achieved targeted sequence integration at high efficiency (up to 40%) via homology-directed repair. This method enabled us to engineer plasma cells to secrete factor IX (FIX) or B cell activating factor (BAFF) at high levels. Finally, we show that introduction of BAFF into plasma cells promotes their engraftment into immunodeficient mice. Our results highlight the utility of genome editing in studying human B cell biology and demonstrate a novel strategy for modifying human plasma cells to secrete therapeutic proteins.

Generation and characterization of pathogenic Mab21l2(R51C) mouse model.

MAB21L2(R51C) is one of the five documented MAB21L2 mutations in human patients with bilateral eye malformations identified via whole exome sequencing. In addition to the eye abnormality, patients with MAB21L2 R51C/+ mutation also have skeletal dysplasia and intellectual disability. To evaluate the pathology of this mutant allele systematically in understanding the functional role of MAB21L2 in human development, we introduce the R51C mutation into the mouse genome by CRISPR/Cas9 system to generate a mouse model for detailed characterization. The Mab21l2 R51C/+ mice have eyeless phenotype and skeletal abnormalities. Micro-computed tomography (micro-CT) analysis showed the Mab21l2 R51C/+ mice have no eye balls but with two abnormal tissues underneath the brain. Histological analysis revealed that the early eye development in the mutant embryos is interrupted. In addition, Mab21l2 R51C/+ mice also have joint fusion phenotype; the humerus is fused with radius, whereas femur is fused with tibia. Limbs in the mutant animals are distinctly shorter than the wild type; and deltoid tuberosities in humeri are absent in these Mab21l2 R51C/+ mice. In summary, we showed that our Mab21l2 R51C/+ mutant mice have recapitulated the pathological features in eye and bone of human patients. Further analyses of the mutant phenotype with molecular markers will provide insight on how MAB21L2 guides the optic differentiation and skeletogenesis, revealing specific underlying pathogenic mechanism of the MAB21L2(R51C) mutation.