Technologies that can safely edit genes in the brains of adult animals may revolutionize the treatment of neurological diseases and the understanding of brain function. Here, we demonstrate that intracranial injection of CRISPR–Gold, a nonviral delivery vehicle for the CRISPR–Cas9 ribonucleoprotein, can edit genes in the brains of adult mice in multiple mouse models. CRISPR–Gold can deliver both Cas9 and Cpf1 ribonucleoproteins, and can edit all of the major cell types in the brain, including neurons, astrocytes and microglia, with undetectable levels of toxicity at the doses used. We also show that CRISPR–Gold designed to target the metabotropic glutamate receptor 5 (mGluR5) gene can efficiently reduce local mGluR5 levels in the striatum after an intracranial injection. The effect can also rescue mice from the exaggerated repetitive behaviours caused by fragile X syndrome, a common single-gene form of autism spectrum disorders. CRISPR–Gold may significantly accelerate the development of brain-targeted therapeutics and enable the rapid development of focal brain-knockout animal models.

Chemical modification of the gRNA and donor DNA has great potential for improving the gene editing efficiency of Cas9 and Cpf1, but has not been investigated extensively. In this report, we demonstrate that the gRNAs of Cas9 and Cpf1, and donor DNA can be chemically modified at their terminal positions without losing activity. Moreover, we show that 5’ fluorescently labeled donor DNA can be used as a marker to enrich HDR edited cells by a factor of two through cell sorting. In addition, we demonstrate that the gRNA and donor DNA can be directly conjugated together into one molecule, and show that this gRNA-donor DNA conjugate is three times better at transfecting cells and inducing HDR, with cationic polymers, than unconjugated gRNA and donor DNA. The tolerance of the gRNA and donor DNA to chemical modifications has the potential to enable new strategies for genome engineering.DOI: http://dx.doi.org/10.7554/eLife.25312.001

Engineering of the Cpf1 crRNA has the potential to enhance its gene editing efficiency and non-viral delivery to cells. Here, we demonstrate that extending the length of its crRNA at the 5′ end can enhance the gene editing efficiency of Cpf1 both in cells and in vivo. Extending the 5′ end of the crRNA enhances the gene editing efficiency of the Cpf1 RNP to induce non-homologous end-joining and homology-directed repair using electroporation in cells. Additionally, chemical modifications on the extended 5′ end of the crRNA result in enhanced serum stability. Also, extending the 5′ end of the crRNA by 59 nucleotides increases the delivery efficiency of Cpf1 RNP in cells and in vivo cationic delivery vehicles including polymer nanoparticle. Thus, 5′ extension and chemical modification of the Cpf1 crRNA is an effective method for enhancing the gene editing efficiency of Cpf1 and its delivery in vivo.

Venous malformations, the most common type of vascular malformation, are slow-flow lesions resulting from disorganized angiogenesis. The International Society for the Study of Vascular Anomalies (ISSVA) classification offers a categorization scheme for venous malformations based on their genetic landscapes and association with congenital overgrowth syndromes. Venous malformations present as congenital lesions and can have broad physiologic and psychosocial sequelae depending on their size, location, growth trajectory, and tissue involvement. Diagnostic evaluation is centered around clinical examination, imaging evaluation with ultrasound and time-resolved magnetic resonance imaging, and genetic testing for more complex malformations. Interventional radiology has emerged as first-line management of venous malformations through endovascular treatment with embolization, while surgery and targeted molecular therapies offer additional therapeutic options. In this review, an updated overview of the genetics and clinical presentation of venous malformations in conjunction with key aspects of diagnostic imaging and treatment are discussed.

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