Experiencing Poor Hearing AND Poor Vision From a Young Age? You May Have 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

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.

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.

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

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

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

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%.

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.

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).

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

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.

Prenatal genetic testing for Usher syndrome is possible through the use of the amniotic fluid.

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).

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.

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.

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.

Usher Syndrome India (USH India, info.india@usher-syndrome.org) 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.