Usher syndrome is an inherited condition that affects both hearing and vision. The symptoms of Usher syndrome consist of childhood-onset hearing loss, progressive vision loss caused by degeneration of the retina (retinitis pigmentosa), and sometimes balance problems.
There are three different clinical types of Usher syndrome, type 1, type 2, and type 3.
Hearing loss is the first symptom to become apparent, usually from birth. Sight loss follows a similar pattern to non-syndromic retinitis pigmentosa; early symptoms include night blindness and reduced peripheral vision, with central vision loss occurring later.
People with Usher type 1 develop profound deafness from birth and sight loss becomes evident in early childhood. The deafness is generally so early in onset and so severe that hearing aids may not be of value, although cochlear implants may be beneficial. Balance is often affected in those with type 1 and can slow the development of sitting or walking.
People with Usher type 2 also experience early onset hearing loss but this is less severe than in type 1. Sight loss usually becomes apparent during the teenage years. Balance is generally not affected.
Usher type 3 is very rare and is generally found in people with their family origins in Finland. Hearing at birth is usually normal but is lost during late childhood and becomes worse over time, with sight beginning to deteriorate during adolescence.
The prevalence of Usher syndrome varies from country to country, but it is a rare condition affecting approximately 1 in 10,000 people. Usher syndrome occurs when there are mutations in genes that are important for the function of the photoreceptors in the retina and the sound-sensing “hair cells” in the cochlea, or inner ear.
So far, researchers have found 11 genes that are associated with the three main subtypes of the syndrome. Usher syndrome occurs equally in both genders and is always inherited in a recessive pattern, meaning that both a person’s copies of the gene must be faulty for the condition to occur. More information about inheritance patterns is available from the About Inherited Sight Loss section of our website.
Current treatment focuses on helping an individual to adapt to hearing and vision loss and to maximising the vision and hearing that they do have. This includes the use of hearing aids, assistive listening devices, cochlear implants, mobility training, and low vision services. The wide range of assistive technologies available provides plenty of choice for users at all stages of sight and hearing loss and this technology has also removed many barriers to education and employment.
Researchers are exploring a number of approaches to treating sight loss in Usher syndrome and there are clinical trials underway. Usher syndrome gene therapy is quite challenging as the genes affected tend to be extremely large in size and difficult to deliver into cells.
However, a project funded by Retina UK is developing a method to safely deliver these large genes. Other approaches include ‘silencing’ the faulty section of genetic code.
Visit the Research News section of our website for updates: https://retinauk.org.uk/category/research-news/.
For up to date information on current clinical trials, visit www.clinicaltrials.gov. Most potential therapies are gene specific, so it’s essential that those living with Usher syndrome are offered genetic testing to allow them to make choices about future treatments and clinical trial participation.
Retina UK is occasionally approached by researchers and companies looking for our help in recruiting participants for studies or patient involvement initiatives, and we can pass on details of opportunities to people on our database who have expressed an interest in these activities and given their consent to be contacted. Anyone who is not already in touch with Retina UK can call 01280 821334 or email info@RetinaUK.org.uk so that we can add them to our database. It is helpful for us to have as much detail about the diagnosis as possible, including genetic diagnosis if available, as some opportunities are condition specific.
The Retina UK Helpline provides information, support and signposting to people affected by inherited sight loss as well as healthcare and education professionals.
Contact 0300 111 4000 (9.30am – 9.30pm Mon to Fri) or Helpline@RetinaUK.org.uk.
Information for professionals is available on the Gene.Vision website: https://gene.vision/knowledge-base/usher-syndrome-for-professionals/.