Usher syndrome (USH) is a rare, genetically inherited disease, and its main symptoms are, sensorineural hearing loss and retinitis pigmentosa (RP) which causes a slow progressive loss of sight. Some people with USH also have vestibular issues too.
Usher syndrome is known to be the leading genetic cause for combined hearing and sight loss, but yet it rare and often under-diagnosed. It's estimated that over 400,000 people worldwide have Usher syndrome. However, since the data on the number of USH patients in Ireland is limited, it's our estimate there could be around 200-260 people living with Usher syndrome here.
USH is inherited in an autosomal recessive manner meaning both parents have passed an USH gene to their child. While a clinical diagnosis of USH can be made through a variety of tests, genetic testing is the only way to confirm an USH diagnosis.
Usher syndrome is catergorised into four major types, 1,2,3, and 4. The chart above represents the typical onset of hearing, sight, and balance loss experienced in each USH type. However, these symptoms are not representative of all those with Usher syndrome as the symptoms can vary in onset and severity.
There are also cases of non-syndromic Usher syndrome, where a person has been genetically tested and has an identified USH gene, but has only one of the symptoms associated with this condition.
Usher Syndrome Types and Subtypes
Usher Syndrome Type 1 (USH1)
USH1B USH1C USH1D USH1f USH1G USH1J
Usher Syndrome Type 2 (USH2)
USH2A USH2C USH2D
Usher Syndrome Type 3 (USH3)
Usher Syndrome Type 4 (USH4)
USH type one and two are the most common types of Usher syndrome with USH type three representing only about 2-5% of overall USH cases. In USH type one, USH1B is the most common subtype representing between 33 – 50% of all USH type 1 cases, followed by USH1D. In USH type 2, USH2A is believed to represent up to 85% of all USH type 2 cases.
RP associated with USH causes the light-sensitive cells in the retina to degenerate. Night-blindness is often the first sign leading to difficulty to seeing in dark/dull settings as well as the time it takes to adjust to different light settings. Over time, the visual field becomes smaller as the loss of the peripheral vision begins, leaving the person with tunnel vision. While many people with USH retain some useful vision until their later years, some do go on to experience a full loss of sight The image provided gives an example of each stage of sight loss.
Usher syndrome causes damage to the tiny hair cells in the cochlea in the inner ear, resulting in a severe impact on hearing. Those with USH1 are typically born with a profound loss, while those with USH2 are born with moderate-severe hearing loss. Those with USH3 and USH4 usually have normal hearing at birth, but experience a progressive loss of hearing over time.
Most people with USH wear hearing aids or cochlear implants giving the user good access to sound. Others rely on sign language to communicate. Where sight loss has progressed to severe, sign language can become difficult for users to follow. Tactile signing is a method used, where a person put their hands under the other person's hands to feel the movements to communicate.
Research into Usher syndrome is progressing at a faster pace than ever before. We have a dedicated section on our website where you can learn more about the different types of research, why patient registries are crucial in finding a cure, and discover the latest USH research news.
Everyone has the right to equal healthcare including accessing and obtaining information in relation to their own healthcare. Therefore it is important for healthcare professionals (HCPs) to ensure when engaging with a patient with Usher syndrome, the patient's accessibility needs are being met thus ensuring the patient has full access to their healthcare.
We have produced a dedicated page on this topic which you should find helpful. Click here to find out more.