What is Usher Syndrome?
Usher syndrome is a condition characterized by partial or total progressive hearing and vision loss.
The hearing loss is classified as sensorineural, which means that it is caused by abnormalities of the inner ear. The loss of vision is caused by retinitis pigmentosa.
There are three types of Usher syndrome – Types 1, 2, and 3.
What are the symptoms of Usher Syndrome?
Babies born with Type 1:
- Are almost totally deaf at birth
- Have severe balance problems
- Sit without support at a later age than normal (normal is at 6 – 9 months old)
- Are late walkers (18-24 months)
- Develop vision problems before age 10, usually in early childhood
- Begins with night vision problems
- Progresses quickly to total blindness
- May not benefit from hearing aids (devices that make sound louder)
- They may be candidates for cochlear implants (a surgically placed device that sends sound directly from ear to stimulate the hearing nerve)
Babies born with Type 2:
- Have moderate to severe hearing loss at birth
- Have normal balance
- Can benefit from hearing aids
- Develop night vision problems as teenagers
- Progresses more slowly
- Does not result in total blindness
Babies born with Type 3:
- Have normal hearing at birth
- Have almost normal balance
- Sometimes have balance problems later on
- Have gradual hearing and vision loss
- Rate of loss differs among children
- Hearing loss is apparent by teens
- Can benefit from hearing aids after hearing loss begins
- Night blindness starts in puberty
- Blind spots occur by late teens/young adulthood
- Total blindness by middle age.
What causes Usher Syndrome?
Usher syndrome is an inherited autosomal recessive disorder.
So far, Usher syndrome has been associated with mutations in at least ten genes:
- Usher syndrome type 1: MYO7A (USH1B), USH1C, CDH23, PCDH15 (USH1F), SANS (USH1G), and possibly CIB2
- Usher syndrome type 2: USH2A, ADGRV1 (previously called VLGR1) WHRN (DFNB31)
- Usher syndrome type 3: USH3A (CLRN1), HARS
How is Usher Syndrome diagnosed?
Diagnosis of Usher syndrome involves personal medical history and testing of hearing, balance, and vision. An eye care specialist can use dilating drops to examine the retina, visual field testing can measure peripheral vision, and an electroretinogram can measure the electrical response of the eye’s light-sensitive cells in the retina.
What are the treatments for Usher Syndrome?
Presently, there is no cure for Usher syndrome. Treatment involves managing hearing, vision, and balance problems.