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Gene editing facilitated by homology-directed repair represents a promising strategy for precisely correcting pathogenic variants underlying monogenic disorders, including the life-threatening skin blistering condition junctional epidermolysis bullosa (JEB). Frequent reports of unintended off-target genotoxicity associated with conventional Cas9 nuclease editing have increasingly led to the adoption of dual-Cas9 nickases (dual-Cas9n) owing to their improved safety profile. However, rates of precise repair obtained with such strategies remain low. In this study, we establish a dual-Cas9n approach targeting LAMB3, using electroporation to deliver Cas9-nickase ribonucleoproteins and modified single-stranded oligodeoxynucleotide repair templates into primary JEB keratinocytes. Targeting a hotspot pathogenic variant (c.1903C>T, p.R635∗), we report perfect correction efficiencies of up to 54% based on standard next-generation sequencing. Using a high-fidelity Cas9 nuclease, we also report perfect repair of up to 74% when using a small-molecule modulator of DNA repair. Dual-Cas9n–corrected JEB keratinocytes demonstrated restored laminin-332 expression and secretion in vitro, leading to improved cellular adhesion and accurate laminin-332 localization in engineered skin equivalents. This protocol represents a significant improvement in precision gene repair using Cas9 nickases for epidermolysis bullosa, with the potential to be applied to a large cohort of patients harboring this prevalent pathogenic variant.

Abstract Gene therapy based on the CRISPR/Cas9 system has emerged as a promising strategy for treating the monogenic fragile skin disorder recessive dystrophic epidermolysis bullosa (RDEB). With this approach problematic wounds could be grafted with gene edited, patient‐specific skin equivalents. Precise gene editing using homology‐directed repair (HDR) is the ultimate goal, however low efficiencies have hindered progress. Reframing strategies based on highly efficient non‐homologous end joining (NHEJ) repair aimed at excising dispensable, mutation‐harboring exons offer a promising alternative approach for restoring the COL7A1 open reading frame. To this end, we employed an exon skipping strategy using dual single guide RNA (sgRNA)/Cas9 ribonucleoproteins (RNPs) targeted at three novel COL7A1 exons (31, 68, and 109) containing pathogenic heterozygous mutations, and achieved exon deletion rates of up to 95%. Deletion of exon 31 in both primary human RDEB keratinocytes and fibroblasts resulted in the restoration of type VII collagen (C7), leading to increased cellular adhesion in vitro and accurate C7 deposition at the dermal‐epidermal junction in a 3D skin model. Taken together, we extend the list of COL7A1 exons amenable to therapeutic deletion. As an incidental finding, we find that long‐read Nanopore sequencing detected large on‐target structural variants comprised of deletions up to >5 kb at a frequency of ~10%. Although this frequency may be acceptable given the high rates of intended editing outcomes, our data demonstrate that standard short‐read sequencing may underestimate the full range of unexpected Cas9‐mediated editing events.

Abstract Background Impetigo is a common and contagious bacterial skin infection, affecting children worldwide, but it is particularly prevalent in socioeconomically disadvantaged communities. In New Zealand, widespread prescribing of the topical antibiotic fusidic acid had led to an increase in antimicrobial resistance of Staphylococcus aureus. Alternative treatments are urgently being sought, and as impetigo is a superficial infection, it has been suggested that topical antiseptics such as hydrogen peroxide or simple wound care alone may treat impetigo while avoiding the risk of increased antimicrobial resistance. Methods This protocol for a non-inferiority, single-blind randomised controlled trial compares topical fusidic acid with topical hydrogen peroxide and with simple wound care in the treatment of childhood impetigo. Participants are randomised to one of the three treatments for 5 days. The primary outcome is clinical improvement assessed through paired photographs analysed by graders blinded to treatment arm. The trial is based in school health clinics in an urban centre in New Zealand. Comparison of antimicrobial resistance patterns pre- and post-treatment is also performed. Discussion Special note is made of the need to involve the communities most affected by impetigo in the design and implementation of the clinical trial to recruit the children most in need of safe and effective treatments. Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR) 12616000356460 . Registered on March 10, 2016 Protocol amendment number: 05 EB and AL contributed equally as senior authors.

Abstract This article presents evidence-based Clinical Practice Guidelines (CPG) for the provision of healthcare services to address sexuality for people living with epidermolysis bullosa (EB). Currently, a lack of EB-specific research limits these services to sexual health assessment and intervention strategies designed for the general population. Due to the unique challenges of EB, a rare skin-fragility condition causing blistering responses to minor skin trauma and other systemic and secondary complications, condition-specific strategies are needed to support people with EB in achieving valued sexual lifestyles. This CPG represents the work of an international panel comprised of thirteen members including a medical doctor, nurses, psychologists, a social worker, an occupational therapist, and patient population involvement members living with EB. It describes the development of EB-specific recommendations for two primary domains of assessment and intervention related to sexuality: psychosocial and mechanical. Following a rigorous evidence-based guideline development process, this CPG establishes the first internationally actionable clinical practice recommendations for sexuality-related assessment and intervention for this population. Future research priorities are identified. Supplemental materials included provide additional support to clinicians in developing the necessary understanding and skills to promote equity and efficacy in this care domain.