Usher syndrome is an autosomal recessive genetic or inherited condition that affects hearing, vision and balance.
Types of Usher syndrome
There are three clinical types of Usher syndrome, Usher one, Usher two and Usher three.
In the UK, Usher one and Usher two are the most common. However, we are finding increasing numbers of people with Usher who have experienced a progressive hearing loss from childhood. These people may have Usher type three.
People with Usher type one are profoundly deaf from birth and have balance problems. Most use sign language as their primary means of communication.
The hearing loss often remains stable throughout a person's life and is generally not helped by hearing aids. However, recently children with Usher one are benefiting from cochlear implants, thereby allowing them to develop speech.
Most children with Usher type one usually begin to develop retinitis pigmentosa-related vision problems between the ages of 8-12 years old, with vision problems first noticed at night, followed by increasing difficulty with side (peripheral) vision. Visual problems will progress.
The balance problems mean that children may be late in sitting up and walking.
Children with Usher two are born with moderate to severe hearing impairment and normal balance. The severity of hearing impairment varies, but many, if not most, children can benefit from hearing aids.
Children are likely to use speech to communicate.
The visual problems related to retinitis pigmentosa (RP) tend to progress more slowly than in Usher one and also tend to begin later, usually in late teenage years, or may not even begin until the person is in their 30s or 40s.
The RP is variable from person to person, so it is impossible to predict how much sight and hearing someone might have at any given stage in life.
The person with Usher two is faced with continually adapting to two changing senses and the impact a change in one sense has on their ability to use the other.
Children born with Usher three have normal hearing. Hearing worsens over time and may progress to profound hearing loss.
However, the rate at which hearing and sight are lost can vary between individuals, even within the same family. Children may develop noticeable hearing problems by their teens and usually are using hearing aids by mid to late adulthood.
Vision problems usually begin during teenage years, starting with night blindness. The sight problems are more variable and this can mean the central vision is affected earlier.
As with Usher two, the RP is variable from person to person, so it is impossible to predict how much sight and hearing someone might have at any given stage in life.
Some people with Usher three will have near normal balance but some may develop problems later on.
As with Usher two, the person with Usher three is faced with continually adapting to two changing senses.
Usher three is rarer in the UK, so diagnosis is often delayed.
So far nine genes have been identified that cause the disorder. They are:
• Type one Usher syndrome: MY07A, USH1C, CDH23, PCHD15, SANS
• Type two Usher syndrome: USH2A, VLGR1, WHRN
• Type three Usher syndrome: USH3A