By Geraldine Rosario
- Usher syndrome is the leading inherited cause of deafblindness (ie, combined hearing loss and vision loss).
- An estimated 56,000 to 280,000 people in India are suspected to have Usher syndrome.
- Early detection and intervention can lead to a healthy and enriching life.
- Usher syndrome researchers want to connect with individuals with Usher syndrome.
What is Usher Syndrome?
Usher syndrome (USH) is the leading inherited cause of combined hearing loss and vision loss (also known as deafblindness). Hearing loss associated with Usher syndrome usually starts at birth or soon thereafter, but it may go undetected for years.
The vision loss associated with Usher is due to a condition called retinitis pigmentosa (RP), which starts with difficulty seeing in dimly lit situations (night blindness) and also causes peripheral vision to slowly deteriorate (tunnel vision). The onset of vision loss depends on the type of Usher syndrome. For some types of Usher, there may also be balance problems.
Usher syndrome accounts for approximately 50% of all inherited deafblind cases 2
What Causes Usher Syndrome?
Usher syndrome is an inherited condition, which means it is directly passed down from parents to their children through genes. When a gene is mutated, it causes certain cells in our body to act differently. To date, researchers have discovered mutations in 11 genes that have resulted in the different subtypes of Usher syndrome.
What are the Types of Usher Syndrome?
Currently, there are 3 known types of Usher syndrome – type 1, type 2, and type 3 – which are further categorized into 11 subtypes. However, there is evidence that more Usher syndrome subtypes have not yet been identified.
What is Usher Syndrome Type 1?
Usher syndrome type 1 (USH1) is characterized by the following:
● Hearing: Profound deafness in both ears from birth
● Vision: Decreased night vision before age 10
● Balance: Balance problems from birth
What is Usher Syndrome Type 2?
Usher syndrome type 2 (USH2) is characterized by the following:
● Hearing: Moderate to severe hearing loss from birth
● Vision: Decreased night vision begins in late childhood or teens
● Balance: Normal balance
What is Usher Syndrome Type 3?
Usher syndrome type 3 (USH3) is characterized by the following:
● Hearing: Normal hearing at birth; progressive loss in childhood or early teens
● Vision: Varies in severity; night vision problems begin in teen years
● Balance: Possible late onset of balance issues
What is the Prevalence Rate of Usher Syndrome?
Prevalence Rates of Usher Syndrome Outside of India:
The prevalence rates in this section are based on research conducted in the United States and the United Kingdom 2
Research has shown that USH1 accounts for 30-40% of all USH cases, USH2 accounts for 56-68%, while USH3 accounts for 2-4%.
Usher Syndrome Type 1 Prevalence Rates by Subtype:
|Usher Subtype||Mutated Gene||Prevalence|
|USH1B||MY07A||30 – 50% of USH1|
|USH1D||CDH23||10 -35%0f USH1|
Usher Syndrome Type 2 Prevalence Rates by Subtype:
|Usher Subtype||Mutated Gene||Prevalence|
|USH2A||USH2A||80 – 85% of USH2|
|USH2C||GPR98 (VLGR1)||15% of USH2|
|USH2D||DFNB31 (WHRN)||5% of USH2|
Usher Syndrome Type 3 Prevalence Rates by Subtype:
|Usher Subtype||Mutated Gene||Prevalence|
Prevalence Rates of Usher Syndrome in India
Based on 2021 research conducted by the L V Prasad Eye Institute in Hyderabad, out of 2,541,810 eye patients seen by a network of hospitals in India, 2 out of every 10,000 patients have been identified to have Usher syndrome, of which 30% had USH1, 36% had USH2, 21% had USH3, while 12% had undetermined Usher type 4
To our knowledge, no research on prevalence rates at the Usher subtype level has been conducted in India.
How Many People Have Usher Syndrome?
Usher syndrome affects approximately 4 to 17 per 100,000 people in the United States5. In India, where the occurrence of inherited diseases is expected to be higher due to marriages within the same community, hospital data suggests that 2 out of every 10,000 eye patients have Usher syndrome 4
This implies an estimated 56,000 to 280,000 people in India are suspected to have Usher syndrome (based on the 1.4 billion population estimate as of June 2022).
What Are the Symptoms of Usher Syndrome?
Usher syndrome affects hearing, vision, and sometimes balance. Hearing loss associated with Usher syndrome usually starts at birth or soon thereafter. The onset of hearing loss often occurs before the onset of vision loss. Here are some symptoms of hearing loss to look out for.
If your child is showing symptoms of hearing loss, consult an ENT doctor (a.k.a. otolaryngologist), or an audiologist.
Symptoms of Hearing Loss in a Child:
- Does not react typically to loud sounds
- Unable to hear faint sounds
- Does not react when you call his/her name
- Misunderstands or misses spoken language
- Speech and/or language development is delayed for his/her age, even with speech therapy.
- Misunderstands or misses spoken language especially when he/she cannot see your lips
- Has trouble understanding conversations when there is some background sound
If your child already wears hearing aids or cochlear implants and is showing symptoms of deteriorating vision (see the table below), consult a retina specialist, or an eye doctor who specializes in inherited retinal diseases (IRDs). During your eye checkup, make sure you mention that your child wears hearing aids or cochlear implants.
For more details, read our article Hearing Loss in Children – What Every Parent Should Know
If your retina specialist suspects Usher syndrome (or another genetic condition), he will conduct a series of tests and may recommend genetic testing.
Symptoms of Retinitis Pigmentosa in a Child:
- Has difficulty seeing in dimly lit areas, at night, or in a dark room
- Often bumps into people or things; appears awkward, clumsy, or accident prone
- Takes longer for his eyes to adjust when going from a bright area to a dark area (like from a sunny outdoors into a dark house) or vice versa
- Sensitive to glare
- Sees halos around lights
- Doesn’t notice people or things to their left or right
- May trip or stumble over items directly in front of them
- Has difficulty seeing the classroom board clearly
- Squints when watching TV
- Holds a mobile phone or tablet very close to his/her eyes
- Cannot see the stars at night
- Easily gets headaches due to glare
- Blindspot(s) in the peripheral vision
- Cannot see something until it is right in front of them
For Usher syndrome type 1 and type 3, a child may also experience balance issues. Here are some symptoms of balance problems.
Symptoms of Balance Problems in a Child:
- Delayed sitting, standing, and walking for his/her age
- Has difficulty walking in a straight line
- May be labeled as clumsy
How does Usher Syndrome Affect the Body?
Usher syndrome affects hearing, vision, and sometimes balance. The hearing loss may be mild but continues to worsen. The eye disease is known as retinitis pigmentosa
How to Test for Usher Syndrome?
Genetic testing (or DNA testing) is the only reliable way to determine if an individual has Usher syndrome. Genetic testing is also the only way to identify the exact subtype of Usher syndrome (by identifying the mutated gene).
Genetic testing is usually done via a blood test. With genetic testing, babies can also be tested, especially when there is a history of Usher syndrome or deafblindness in the family.
In India, there are genetic testing labs that test for Usher syndrome.
Are There Prenatal Tests for Usher Syndrome?
Prenatal genetic testing for Usher syndrome is possible through the use of the amniotic fluid.
How to Diagnose Usher Syndrome?
When there is no family history of Usher syndrome and no other reason to undergo genetic testing, individuals usually get diagnosed with Usher only after they start to experience symptoms of retinitis pigmentosa (the vision loss component of Usher), which in turn, often occurs after the individual has already been diagnosed with hearing loss.
Diagnostic examinations for hearing loss may include newborn hearing screening, audiometry test, BERA test, HR CT, and MRI of the temporal bones.
Diagnostic examinations for retinitis pigmentosa (vision loss) may include a dilated eye exam, electroretinogram (ERG), visual field test, optical coherence tomography (OCT), and fundus autofluorescence (FAF) imaging.
Diagnostic examinations for balance problems may include videonystagmography (VNG), vestibular evoked myogenic potentials (VEMPs), and video head impulse test (v-HIT).
Is Usher Syndrome Inherited?
Usher syndrome is an inherited condition.
An individual with Usher syndrome of a specific subtype is someone who has 2 copies of the mutated gene associated with that subtype, one copy passed down from the mother, and the other copy passed down from the father. If an individual has only one copy of the mutated gene, then that individual is said to be a “carrier”, and will not exhibit any symptoms of Usher.
If both parents are carriers of the same Usher gene, then their child will have a 25% chance of inheriting 2 copies of the Usher gene (hence, will have Usher syndrome), a 50% chance of inheriting 1 copy of the Usher gene (hence, will be a carrier), and 25% chance of not having the Usher gene. If both parents have Usher syndrome of the same subtype, then all their children will have Usher syndrome of that subtype.
Because of this inheritance pattern, individuals with Usher syndrome or who are carriers of Usher syndrome may choose to seek genetic counseling before starting a family.
Why is Early Detection and Intervention of Usher Syndrome Important?
Early detection and early intervention of Usher syndrome are crucial in ensuring that a child with Usher gets the best possible education early in life, including tools, techniques, and accommodations to support their unique learning style. This will give the child the best opportunity to lead a healthy and enriching life.
Early detection also gives parents the time to plan for the future: what life skills to teach their child early in life, how to save/invest for future educational and medical expenses, how to strengthen the family’s emotional and mental health, what skills can a parent learn to help a child live a better life, etc.
Is Usher Syndrome Curable?
There is currently no cure for Usher syndrome, but there are a LOT of treatments available to mitigate hearing loss, vision loss, and balance issues.
There is also a growing international Usher community eagerly looking for more treatments and a cure, and a growing research community specifically focused on finding ways to slow/stop/reverse the vision loss, hearing loss, and balance issues associated with Usher. To facilitate the connection between the Usher community and Usher researchers, the international USH Trust Registry was created in 2008.
A comprehensive list of treatments and research projects focused on Usher syndrome is available on the Usher Syndrome Coalition website.
To receive information on or participate in the latest research, treatments, and clinical trials, register in the USH Trust Registry.
Are There any Usher Syndrome Support Groups in India?
Usher Syndrome India (USH India, email@example.com) is a support group that caters to the unique needs of the Usher syndrome community in India. USH India was started in 2020 by the international organization Usher Syndrome Coalition, which has been serving the global Usher syndrome community since 2008.
 Usher Syndrome Coalition. www.usher-syndrome.org
 Genetics and pathological mechanisms of Usher syndrome. By Denise Yan and Xue Z Liu. 2010. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4511090/
 National Eye Institute. www.nei.nih.gov
 L V Prasad Eye Institute, Hyderabad https://journals.lww.com/ijo/Fulltext/2022/07000/Retinitis_pigmentosa_in_Usher_syndrome_in_India_.59.aspx
 National Institute on Deafness and Other Communication Disorders. https://www.nidcd.nih.gov/health/usher-syndrome
About the Author
Geraldine Rosario is a Mumbai-based volunteer ambassador of the Usher Syndrome Coalition for India. Her mandate: to increase awareness about Usher syndrome in India, help accelerate research, and provide support to the Usher community in India. As a mom to a wonderful boy with Usher syndrome, she is driven to find ways to slow down the progression of his hearing and vision loss, and to connect with families living with Usher. As a statistician and computer scientist, she is currently involved in analyzing Usher 2 patient data.