Light at the end of the Tunnel - determining the genetic cause for Childhood Retinal Blindness

Associate Professor Andrea Vincent
University of Auckland

What is the problem and who does it affect?

Childhood blindness due to inherited retinal disease affects around 3-4 children in every 10,000. These diseases constitute a significant social and economic burden. Besides the obvious difficulties, children can also feel socially stigmatised because of their vision impairment. Other research highlights poorer health outcomes and developmental delay for these children.

Two of the diseases, considered to be at the more severe end of the spectrum, are leber congenital amaurosis (LCA) and early-onset severe retinal dystrophy (EOSRD). Children with these conditions present early at birth with common features symptomatic of these diseases; poor vision and roving eye movements. There are an estimated 56-140 children affected in New Zealand.

Advances in gene-sequencing and gene therapies represent exciting and novel opportunities for more accurate diagnosis and potential treatment. The first gene-replacement therapy was recently successfully completed for an LCA gene. However, for children to participate in clinical trials, the price of admission, so to speak, requires a fully sequenced genome, and a genetic diagnosis.

 

What does this project hope to achieve?

Dr Andrea Vincent and her team from the University of Auckland are setting about doing just that. They have identified 41 children from the NZ Database of Inherited Retinal Disease, for which 25 have no genetic diagnosis.

Vincent and her team will screen each of the children against a gene panel composed of over 280 genes associated with retinal disease in children with LCA/EOSRD. This will likely result in a genetic diagnosis for some, improving the chances of them being eligible for a clinical trial and, most importantly, the potential for treatment. The genetic data will be correlated with the clinical features of each child, which could lead to more targeted genetic testing in future cases.

The team are confident they’ll identify the underlying genetic cause for over 70% of the children. This would offer some hope to families as to what the future might hold with more targeted and individualised treatments.

The flip side of this is, an estimate 30% will remain uncharacterised. The researchers are excited by this as it may pave the way for the discovery of new disease-causative genes. Therapies such as gene-sequencing, gene editing, or stem-cell therapies are exponential in their rise. It’s critical that New Zealand keeps up, so that our children with inherited retinal blindness, and other diseases, have early access to these treatments.