CRISPR activation for inherited blindness

Brief Lay Background

Dominant optic atrophy (DOA) is the most common genetic disease that affects the optic nerve, causing progressive and irreversible blindness with a prevalence of 1:25,000 in the UK.

DOA has an insidious onset in early childhood and typically presents with bilateral, symmetrical, central visual loss and affects the ability to distinguish between colours (dyschromatopsia), caused by the loss of retinal ganglion cells (RGCs). Visual loss is progressive, and the majority of patients are registered legally blind by the fifth decade of life. 60 to 70% of cases of DOA are caused by disease associated variants in the OPA1 gene.

What problem/knowledge gap does it help address

There are currently no treatments that can slow down or prevent loss of vision DOA. Loss of vision in DOA occurs because a population of specialised nerve cells that make up the optic nerve, known as retinal ganglion cells (RGCs), start to malfunction before dying.

Most patients with DOA inherit a faulty copy of the OPA1 gene from one of their parents, resulting in lower levels of the OPA1 protein that is insufficient for cell activity. It is not understood why the loss of OPA1 leads to nerve cell death, but increasing the amount of OPA1 could be a potential way to save these cells and treat DOA to preserve vision.

Aim of the research project

To use gene-editing technique CRISPRa to replace the damaged OPA1 gene to properly express a functioning protein.

Key procedures/objectives

1. Study the effect of CRISPR activation (CRISPRa) in a range of cell models to investigate its potential to modify gene expression
2. Monitor how different guide RNAs (gRNA) for CRISPRa affects OPA1 transcript level and splicing to assess protein levels.
3. Test in patient-derived models how CRISPRa can affect markers for reduced OPA1 function
4. Assess potential off-target effects of the CRISPRa

Potential impact on people with sight loss

This research is important because there are currently no effective treatments for DOA. Disease-associated variants in OPA1 are the major cause of the condition. Gene augmentation has shown some promise in preclinical models of DOA, but there are concerns that overexpression of OPA1 could be deleterious with an adverse effect.

The student will explore if enhancement of the OPA1 gene via CRISPRa will restore the full range of the OPA1 function.

The findings from the project will also be important for other dominantly inherited ocular diseases. This research will also lay the foundations for the use of CRISPRa as a research tool or as a translational method which can be applied to a wide range of genes.