Experimental Gene Therapy for Norrie Disease Shows Promise in Mice

Rare Daily Staff

Researchers have developed an experimental gene therapy that significantly reduces the hearing loss associated with Norrie disease in a mouse model.

Norrie disease is a rare but devastating genetic disorder that causes blindness and hearing loss, and it primarily affects boys. They are born blind and from about 12 years of age develop progressive hearing loss.

An international team led by researchers at UCL and the NIHR Great Ormond Street Hospital Biomedical Research Centre developed the gene therapy to slow or prevent the hearing loss and the dual sensory deprivation that severely restricts the lives of those with Norrie disease.

Currently, the only possible treatment option is cochlear implants, which are only partly effective in Norrie disease. This research in mice, published in the journal EMBO, has shown how a gene therapy can be used to prevent the death of the vitally important hair cells in the cochlea—the snail shell-like part of the inner ear responsible for sensing sound—and stop the loss of hearing associated with Norrie disease.

The team injected a gene therapy designed to restore the missing norrin protein. They showed that the abnormal blood vessels in the ears and eyes that develop in mice with Norrie disease are improved by the treatment. Tests showed both better hearing and vision after the gene therapy treatment in mice.

“Children with Norrie disease progressively lose their hearing because of a faulty gene called NDP, which is responsible for some of the structures in the inner ear,” said James Wawrzynski from UCL Great Ormond Street Institute of Child Health, co-author on the study. “In our study we have shown that in mice with Norrie disease, we can correct this faulty gene by inserting billions of new ‘fixed’ copies into the bloodstream. This gene therapy appears to lead to better blood vessel structure in the inner ear and crucially we can see the sensory hairs are protected.”