Frequent Questions

This section is a compilation of answers to the questions most commonly asked about Usher syndrome. Just start by following one of the links below for detailed answers. If you can’t find the question you wanted to ask, don’t hesitate to contact us at info@usher-syndrome.org.

  1. What causes Usher syndrome?

    Usher syndrome is inherited, which means that it is passed from parents to their children through genes. Genes are located in almost every cell of the body. Genes contain instructions that tell cells what to do. Each person inherits two copies of each gene, one from each parent. Sometimes genes are altered, or mutated. Mutated genes may cause cells to act differently than expected.

    Usher syndrome is inherited as an autosomal recessive trait. The term autosomal means that the mutated gene is not located on either of the chromosomes that determine a person's sex; in other words, both males and females can inherit Usher syndrome and can pass the Usher gene to their child. The word "recessive" means that to have Usher syndrome, an individual must receive a mutated form of the Usher syndrome gene from each parent. If a child has a mutation in one Usher syndrome gene but the other gene is normal, he or she is predicted to have normal vision and hearing. Individuals with a mutation in a gene that can cause an autosomal recessive disorder are called carriers, because they “carry” the gene with a mutation but show no symptoms of the disorder. If both parents are carriers of a mutated gene for Usher syndrome, they will have a one-in-four chance of having a child with Usher syndrome with each birth.

    Usually, parents who have normal hearing and vision do not know if they are carriers of an Usher syndrome gene mutation.

    This content was generously provided by the National Institutes of Health. For more on Usher syndrome from the NIH, please visit their website.

  2. How many types of Usher syndrome are there?

    There are three clinical types of Usher Syndrome:

    Type 1 – causes profound deafness. Vision loss cause by retinitis pigmentosa (RP) may be noticed before the age of 10. Poor balance is often associated with Usher type 1, which causes delay in the age of sitting and walking. Many adults with Usher 1 communicate with sign language and identify as a culturally Deaf. Children with Usher type 1 who receive cochlear implants at an early age usually communicate using speech and lip-reading.

    Type 2 – causes a moderate hearing loss. RP may not become apparent until adolescence. Speech assisted by the use of lip-reading and hearing aids will usually be their primary method of communication. Balance is not affected.

    Type 3 – is the rarest form of Usher syndrome. It occurs with higher frequency in people of Ashkenazi Jewish and Finnish ancestry. Children usually have normal hearing and sight at birth, then develop hearing loss and RP in adolescence or later. Hearing can deteriorate steadily over ten or fifteen years. Some with type 3 also experience balance problems.

    There are at least eleven different genetic types of Usher syndrome, as determined by the genes that are involved. There are six different genes that cause Usher type 1, three that cause Usher type 2, and two that cause Usher type 3. One cannot determine the genetic type by clinical testing; DNA testing is the only reliable way of determining the true genetic type.

    Individuals with Usher type 1 are typically profoundly deaf whereas those with type 2 are usually hard of hearing. People with Usher type 1 also experience balance problems from birth. This causes them to usually start walking later than their peers. Children with type 2 walk at the typical age of 10 to 14 months. The RP of Usher type I is often diagnosed earlier that that for type 2, though recent breakthroughs in genetic testing are allowing for earlier diagnosis of all types of Usher syndrome

  3. What is Retinitis Pigmentosa?

    How Retinitis Pigmentosa Works
    Retinitis pigmentosa (RP) is a disease of the retina cells in the eye that are known as the rods. The retina is the light sensitive tissue of the back of the eye where the first stage of “seeing” take place. With RP the retina slowly degenerates and loses its ability to transmit pictures to the brain. The early symptoms of RP include difficulty seeing in the dark, often coupled with problems in adapting to bright light and changing light conditions. A later symptom is a loss of ability to see to the periphery, also called tunnel vision.

    Rods are located in the retina and are mainly responsible for our ability to see dim light. Also, because they are located in the periphery of the retina, they help in peripheral vision. Because it is genetic, RP is actually present at birth, but it does not become detectable until later.

    Night blindness
    This refers to the inability to see in dim light. During twilight or at night, people with RP will have a great difficulty in seeing. In fact, a child who might see perfectly well during the day may be blind once the sun goes down. The first symptom is usually difficulty in situations where the level of light is low, like a movie theater. This is often present at an early age. Children with RP are sometimes reluctant to go out at night and may insist on a light during the night when sleeping. They may have difficulty in going from bright to dark lighting.

    Tunnel Vision
    In RP the cells at the edge of the retina gradually stop sending information about changes in light levels and the shape of objects on the edge of someone’s vision. This loss of visual field, or “tunnel vision” means that someone cannot see objects unless they are directly in front of him. This may mean for example, that they can still read books and a computer screen, but will need help to keep from running into things and tripping over low obstacles. As the RP progresses their ability to see out toward the sides and the top and bottom of their visual field decreases. The peripheral vision gradually decreases until they have a severe tunnel vision as adults

    Follow this link to get answers to common questions about RP from the Foundation Fighting Blindness.

  4. Does Usher syndrome always result in blindness?

    Very few people with Usher syndrome will become totally blind – that is, have no light awareness.

    Most children will be night blind but will keep their normal vision for reading and seeing fine detail so long as good lighting is available. Loss of visual field is also common, which means someone’s ability to see around them (rather than straight ahead). This causes problems for people in moving around safely, especially in unfamiliar places. Sometimes children with Usher appear to be clumsy because they trip over obstacles on the ground that they cannot see. Many people with Usher syndrome will also find it difficult to judge depth, or to see monotones (such as grey, white and black), and find that they are easily dazzled by bright light.

  5. Why is early diagnosis important?

    Early diagnosis is critical for children with Usher syndrome. While there is no definitive cure for Usher syndrome, there are a LOT of treatments. There are treatments for hearing loss, treatments for balance issues, and, yes, treatments for vision loss. And many of these treatments are most successful when begun very early in life.

    In short, there is something that can be done. Lots of somethings. But you need a definitive diagnosis and you need it as early as possible. Here are just some of the reasons why early diagnosis is a good thing for a family:

    Communication Skills
    Kids with Usher syndrome have hearing loss. Regardless of the communication method a family chooses, be it Sign Language or oral communication, early detection is the key. Most language is developed in the first five years of life. You need to get started right away and knowing whether you’re dealing with Usher needs to be part of the decision process.

    Safety Concerns
    A child with hearing loss does not need mobility training, but a child with Usher syndrome might. Many parents of children with Usher report suspecting that their child had problems seeing at night, but they often only recognize it after an accident has occurred.

    Balance is also a concern in families with Usher. Riding a bike or ice skating or simply hiking a steep trail can be dangerous for kids with Usher. Not undoable, mind you, but dangerous without the proper preparation. Parents plan ahead when they have a diagnosis where they might not without it.

    Educational Support Planning
    Vision problems can hinder a child’s ability to learn. A child with night vision problems might not do as well in an astronomy class, for instance, when he or she can’t see all the stars in the sky. It needs to be part of a child’s Individual Education Plan. Families that have a child with undiagnosed Usher syndrome often only consider hearing as part of the IEP, not vision. Early diagnosis changes that and changes it before the unexplainable struggles start to appear.

    Treatments
    Yes, treatments. Not cures, mind you, but viable, regularly prescribed treatments. Some of these are controversial and you should discuss them with your physician before embarking on them, but they are treatments none the less. And they are treatments that are not even mentioned unless a child is diagnosed with Usher syndrome.

    Future Clinical Trials
    There are treatments nearing or in clinical trial that hold the hope of slowing, stopping, or even reversing the vision loss associated with Usher syndrome. But almost all of these treatments are diagnosis specific. In other words, it’s not enough to suspect Usher syndrome. You have to know definitively and you have to know the specific genetic cause.

    Family Planning
    Many families of children with hearing loss ask the question “will my next child have hearing loss, too?” Usher syndrome is an autosomal genetic disorder. Each child born to carrier parents has a 25% chance of having Usher syndrome. Parents can only take this into consideration when planning a family with a definitive diagnosis.

    Satisfies the Need to Know
    This argument for early diagnosis is the most ambiguous but also might be the most important. It removes the doubt. There are thousands of adults with Usher syndrome living happy, productive lives. Knowing gives families a chance to act, to take control of their child’s care.

  6. How does basic genetics apply to Usher syndrome?
    How does basic genetics apply to Usher syndrome?

    All of the genes in our bodies are made of a chemical called DNA (deoxyribonucleic acid). DNA is a chemical made of four kinds of building blocks, or bases: adenine (A), cytosine (C), guanine (G), and thymidine (T). These bases can be strung together in many different combinations to create unique DNA sequences. Genes are made of these sequences and contain the instructions for life. A small part of a gene might have a DNA sequence that looks like this:

    ATTCTGATTTAAGCTA.

    In total, humans have about 100,000 different genes that are grouped into small structures called chromosomes. People have 23 pairs of chromosomes, including a pair of sex chromosomes. Each pair consists of one chromosome that is inherited from the mother and another chromosome that is inherited from the father. The sex chromosomes contain genes that determine the sex of a person. Girls inherit two X chromosomes, whereas boys receive one X chromosome and one Y chromosome.

    Because people have two versions, or copies, of every chromosome, they therefore have two copies of every gene. The DNA sequences of these genes are more or less the same in everyone. However, sometimes there is a difference in one person's gene sequence as compared to the majority of the population. This DNA change is called an alteration, or mutation. Some mutations may occur that do not interfere with the health of an individual. Other mutations disrupt the gene enough so it does not function correctly. Below is an example of a mutation in a gene associated with hearing. The base change from G to T is enough to alter the instructions contained in the DNA sequence.

    ... A G A T G A G C A ... Normal sequence = Working gene
    ... A G A T T A G C A ... Mutated sequence = Non-working gene

    Gene mutations can be dominant or recessive. The Usher syndrome mutation is recessive. In this case, the altered gene is not strong enough to have an affect if a person also has one unaltered gene. As a result, an individual must inherit two altered genes, one from each parent, in order to be affected. The term carrier is used to describe a person who has one unaltered gene and one gene with a recessive mutation. This person is not affected but can pass on that mutation to his or her children. Because many Usher syndrome parents are carriers, Usher syndrome often appears in families with no history of Usher syndrome.

  7. What is a genetic test?

    A genetic test determines the DNA sequence of a certain region of the human genome. This region could be a whole gene, a portion of a gene, or other areas thought to regulate genes. The test will look for certain changes in the sequence that are known to have consequences on the function of a gene. These tests can be used to:

    1. diagnose a disease or other trait,
    2. determine if a person is a carrier of a mutation that could lead to disease in their children, and
    3. predict if a disease or trait that is not yet detectable by other medical tests may occur in the future.
  8. How are genetic tests performed?

    Most genetic tests are performed on a DNA sample. Because every tissue in the body is made of cells that contain DNA, any tissue can be used as a source of DNA. However, blood is the most common source because it can easily be obtained in large quantities; typically 5-10 ml (1-2 teaspoons) are taken for a test. Some laboratories will allow cheek cells to be submitted for genetic testing. In this case, the cells are usually collected by rubbing the inside of the mouth with a small brush.

    After the DNA is obtained from a blood or other tissue sample, a variety of different methods can be used to look for mutations in your genes. Sometimes the whole coding sequence of the gene is examined. This is similar to reading a page in a book to look for spelling errors in all of the words. Other times, methods are used that only look for the most common mutations. In this case, the test is similar to looking at a page only for a specific misspelled word and ignoring all of the other words. Some laboratories may combine these methods by first screening for common mutations and then, in certain circumstances, examining the whole coding sequence of the gene. Different laboratories may test for a different number of Usher genes.

  9. Why is genetic testing helpful?

    If you are visiting this website, chances are you suspect that you or a family member has Usher syndrome. The only way to know for sure is through genetic testing. Knowing can lead to improved decisions about treatment and management. In addition, genetic testing can help determine if other problems related to Usher syndrome besides hearing loss may be present or may develop in the future.

    In addition to improved treatment choices, genetic information may help in other ways. Genetic testing can provide an individual or the parents of a child with the satisfaction of understanding the cause of certain physical issues. It can also be useful when making reproductive choices because once a genetic cause is identified, it is then possible to predict the likelihood that future children of that person will also have Usher syndrome. In general, how people use genetic information will vary widely depending upon individual perspectives about hearing loss, religious beliefs, and other factors.

    Regardless of how the genetic information is used it can be an overwhelming and stressful experience for people to learn that a mutation in their own genes is the cause of their child's situation. It should be remembered, however, that genetic mutations are very common. All people carry gene mutations that might affect their health or physical characteristics. Mutations in some genes may cause medically important conditions, while others explain many of the normal differences between people. No person is responsible for the particular genes he or she possesses.

    These benefits and drawbacks of genetic testing must be understood by anyone considering testing so that an informed decision about testing can be made. Genetic counselors are skilled in educating others about genetic testing and its many associated issues. You should feel free to contact a counselor or doctor if there is any information about genetic testing that is unclear, or if you would like to discuss your particular situation.

  10. How does a child inherit a recessive mutation?
    How does a child inherit a recessive mutation?

    Children receive one copy of each chromosome from their mother (shown in green) and one copy from their father (shown in blue). In this image, a red band represents a recessive mutation in a gene on one copy of the father’s chromosomes and a second red band represents a recessive mutation in the same gene on one copy of the mother’s chromosomes. Each child has a 50% chance of receiving the copy with the recessive mutation from either parent. But, in the case of recessive mutations, both copies need to be altered for an individual to be affected. The chance of two events happening at the same time can be found by multiplying the chance of the two separate events together.

    (chance of receiving mutation from father) x 1/2
    (chance of receiving mutation from mother) x 1/2
    = (chance of receiving two mutations) 1/4

    Therefore, in each pregnancy, there is a 25% chance that the child will inherit both mutations and, on average, 1 out of 4 children will be have Usher syndrome.

  11. How are the results of an Usher gene test interpreted?

    There are four possible outcomes to an Usher gene test:

    No mutations are detected:
    If no mutations are found, and the entire coding sequence was analyzed in a gene, it is unlikely that the hearing loss is caused by mutations in that specific gene. However, the patient may have Usher syndrome due to mutations in another gene that causes Usher syndrome. Not all genes for Usher syndrome have been identified.

    Two mutations are detected:
    If two identical mutations or two different mutations in the same gene are found, and these mutations have been previously found to cause Usher syndrome, it can be assumed that the hearing loss is caused by these mutations.

    Only one mutation is detected:
    If only one mutation is detected, interpretation can be difficult.

    • It is possible that the test did not detect the second mutation. Even though examining the whole coding sequence of the gene will detect most mutations, there are other regions of the gene sequence and surrounding DNA that could contain a mutation. Unfortunately, these sequences are rarely analyzed unless a specific mutation is already known.
    • The mutation that was found may be unrelated to the hearing loss.

    Mutations were detected but their significance is unknown:
    Some changes in these genes are not considered to affect the function of the gene. These changes are often called “polymorphisms”. Sometimes, a new mutation is found and it is not yet clear whether the change will cause hearing loss or not. Unfortunately, more studies would need to be done before a definite conclusion could be made.

  12. How much does a genetic test cost?

    The cost and turn-around-time of a genetic test may vary depending on the lab and the methods used for testing. Some Usher screens cost around $500. More accurate and detailed testing may cost between $2000-$5000. A typical range of time to get the results might be 8-12 weeks. Insurance companies will often pay for genetic tests, but you should check with your company before your doctor orders the test.

  13. What are the research areas into potential treatments?

    Research into effective treatments for Usher syndrome is focused on four main areas: gene therapy, retinal implants, stem cell therapy and drug-based therapy. For the latest news on these and other research, click here.

    Gene Therapy
    In 2008, researchers at the University of Pennsylvania and Children’s Hospital of Philadelphia used gene therapy to safely restore vision in three young adults with Leber’s Congenital Amaurosis (LCA), a rare and severe form of congenital blindness. According to Albert Maguire, ophthalmologist at the University of Pennsylvania, “Patients’ vision improved from detecting hand movements to reading lines on an eye chart.” One year later, the patients continue to enjoy the same level of improved vision, and the clinical trials have been expanded to include new patients. For more on this topic, click here.

    Many genetic diseases, including Usher syndrome, are caused by a spectrum of different mutations that include a type of mutation called a nonsense mutation. PTC Therapeutics has produced a drug, initially known as PTC 124, now called Ataluren, that has been successful in clinical trials for a subset of patients with Duchenne Muscular Dystrophy and Cystic Fibrosis, who harbor a nonsense mutation. These two diseases have initially been targeted due to their reasonably large patient populations, however, Ataluren may be effective in treating other diseases in which a subset of patients harbor nonsense mutations. A lab in Germany is testing the drug in a mouse model for one of the mutations that can cause Usher 1C via direct administration to retinal cells. For more on this topic, click here.

    Usher syndrome 1f is another type of Usher syndrome in which a subset of patients harbor a nonsense mutation. One particular mutation runs in Ashkenazi Jews. Researchers at the Technion in Israel discovered that, like Ataluren, a class of antibiotics, aminoglycosides, can counteract nonsense mutations. Gentamicin is an aminoglycoside. However, continued use of gentamicin is not feasible as, at the constant daily doses that would be required, it would be toxic to humans. Dr. Tamar Ben-Yoseph, a geneticist at the Technion who specializes in Usher Syndrome, collaborated with Professor Timor Baasov of the Chemistry department to modify aminoglycosides to make them safe for humans. The results was NB54, a derivative of gentamicin. The team has been testing NB54 in the lab and is working to obtain an animal model for the next phase of testing. For more on this topic, click here.

    Retinal Implants
    The U.S. Department of Energy is funding through 2010, and possibly beyond, the development of an artificial retina. The implant is a collaborative effort between the U.S. government, private industry and research universities. Clinical trials are underway for a 16 and 60 electrode version, The Argus I and II respectively, and development of the next generation with even more electrodes is underway. The implant works similarly to a cochlear implant, with a small camera mounted on glasses that sends a signal to the electrode array implanted on the retina. For more on this topic, click here and here.

    Researchers at the Massachusetts Institute of Technology are working a retinal implant that works similarly to the Argus implant with glasses and a camera. The chip will be implanted outside of the retina with only the electrodes attached to the retina. MIT hopes to begin clinical trials in three years. For more on this topic, click here.

    Click here to learn about other countries and teams also researching retinal implants.

    Stem Cell Therapy

    Several researchers are working to use stem cells to create new retinal cells to replace damaged ones. At SUNY Upstate Medical University in Syracuse, N.Y., researchers were able to convert frog stem cells into retinal cells. These cells developed into functioning eyes, enabling the tadpoles to see. For more on this topic, click here.

    Researchers at the University of Washington in Seattle are working to use stem cells to replace damaged retinal cells. They have succeeded in creating retinal cells from stem cells and are implanting these cells into blind animal models. For more on this topic, click here.

    Advanced Cell Technology (ACT) in Cambridge, MA, working with collaborators at Oregon Health and Science University, have created human embryonic stem cell (hESC)-derived retinal pigment epithelium (RPE). They have already implanted these cells into mouse and other animal models. Robert Lanza, Chief Scientific Officer at ACT, states that the company is preparing to apply to the FDA to begin clinical trials in humans. For more on this topic, click here.

    Using a type of skin cells known as human iPS cells, researchers at the University of Wisconsin-Madison School of Medicine and Public Health have successfully grown multiple types of retina cells, paving the way for repairing damaged retinas with new cells grown from the patient’s own skin. For more on this topic, click here.

    Drug-based Therapies
    Ciliary Neurotrophic Factor (CNTF) or NT-501 is a drug-based therapy from Neurotech. Using Encapsulated Cell Technology (ECT), surgeons deliver CNTF directly into the eye via implanted capsules. Phase 2 clinical trials for retinitis pigmentosa are complete. Several patients have experienced improved visual acuity following the implants. The FDA has fast tracked CNTF, meaning that, once clinical trials are complete, the FDA will expedite review of the results. For more on this topic, click here.

    Researchers at the Schepens Eye Research Institute in Boston discovered which chemicals in the eye, glutamate and aminoadipate, cause other cells to transform into retinal progenitor cells. These cells are similar to stem cells and regenerate new retinal cells. Testing in the lab and in mice showed that the cells became progenitor cells, migrated to the correct locations in the retinas, and developed into new retinal cells. For more on this topic, click here.

  14. What is Usher Syndrome Type I?

    Usher syndrome type 1 is a genetic disease. It is inherited in a manner that geneticists call recessive. This means that an Usher 1 gene must be inherited from each parent in order for the child to have Usher type 1. In other words, both parents are carriers and they have a 1 in 4 chance of passing both copies of the Usher gene to each child.

    People with Usher type 1 are usually born profoundly deaf and experience progressive vision loss due to a retinal disease called retinitis pigmentosa (RP). The symptoms of RP are difficulty seeing in dimly lit areas - or night blindness - and a gradual loss of peripheral vision. These symptoms will generally begin in the teen years and continue through adulthood. Today, Usher syndrome is usually diagnosed before adulthood, but older people still report that the diagnosis wasn’t made until later in life when the vision loss from RP became severe enough to interfere with their mobility. People with Usher type 1 often also have vestibular issues which manifest as an inability to balance normally. This can become more pronounced as their vision degrades. Balance issues manifest early in children with Usher type 1, as they often learn to walk later than their peers.

    Carriers of Usher Type I
    When only one Usher type I gene is passed on, half the normal amount of its protein is produced. It is believed that this is sufficient for normal vision and hearing as no clinical symptoms result. Certainly, there have been no reports of vision and hearing loss in those who are carriers for any of the Usher genes. However, there are theoretical reasons to think that there may be very mild hearing and vision problems that occur with older adults but to date this has not been studied.

    Hearing in Type I
    Hearing loss in children with Usher syndrome type 1 is usually severe to profound and present at birth.

    Vision in Type I
    A person with Usher 1 may become legally blind as a young adult primarily because of severe tunnel vision. Central vision is usually retained into adulthood, allowing individuals to continue to read print and use a computer. Some adults with Usher 1 will lose central vision more quickly, retaining only light perception.

    Balance in Type I
    Individuals with Usher type 1 often have limited vestibular functionality. This can result in severe balance issues. Children with Usher type I are often late walkers or late sitters. It is not uncommon for children with type I Usher to begin walking at 24-36 months. These balance issues are present throughout life and often become more pronounced in low light or as the vision degrades.

    Physical and occupational therapy can help individuals with type I with their balance issues. Core strengthening and hippotherapy can improve a person's ability to compensate for the decreased vestibular functionality. Mobility training can also be also helpful.

    Genes involved in Type I
    Usher syndrome type I is the most severe form of Usher syndrome and is characterized by congenital, profound sensorineural hearing loss, vestibular dysfunction, often manifested as delayed walking (>18 months), and the onset of RP by the age of ten (Keats and Lentz, 2006). Usher syndrome type I is further subdivided into 5 types. Mutations in the MYO7A, USH1C, CDH23, PCDH15, and USH1G (SANS) genes cause Usher syndrome type 1B, type 1C, type 1D, type 1F and type 1G respectively.

    Mutations in these genes account for most cases of Usher syndrome type I. Mutations in MYO7A are the most common accounting for 39-55% of cases (Keats and Lentz, 2006). An Ashkenazi Jewish founder mutation, R245X, has been identified on the PCDH15 gene which has a carrier frequency of up to 2.5% in this population. MYO7A, USH1C, CDH23, and PCDH15 mutations have also been reported in several families with recessive nonsyndromic hearing loss. In addition, a few families with autosomal dominant nonsyndromic hearing loss (DFNA11) have also been described with mutations in MYO7A.

    Although these are the most common characteristics of Usher syndrome, due to mutations in these genes, there can be variations. Overlapping and atypical presentations have been described for all three types of Usher syndrome. For example some individuals with mutations in type I genes may have a milder presentation (moderate hearing loss and/or a normal vestibular system). In addition, certain genes (MYO7A, USH1C, CDH23, PCDH15, and DFNB31) can cause isolated hearing loss without developing retinitis pigmentosa.

    Identified disease causing mutations in all of these genes include missense, nonsense, frameshift, splice-site as well as deletions distributed across nearly all exons.

    Usher Type I subtypes
    Although all individuals with Usher type 1 demonstrate similar symptoms, the genetic causes differ. Some are more common than others. Usher subtype 1b is by far the most common form of Usher type 1 and accounts for over 40% of all cases. Subtype 1d appears to be next most common and is responsible for about 25% of all cases. Usher Ic is not very common in the general USA population, but it is common among French Acadians in Louisiana. Usher 1f and 1g are uncommon and so far only a few cases have been reported. There is a form of Usher 1f that is common among people with Ashkenazi Jewish ancestry. Usher 1a does not exist and 1e is quite rare. There is evidence that there are more Usher 1 subtypes that have not yet been identified.

  15. What is Usher Syndrome Type II?

    People with Usher type 2 are born hard of hearing and then develop a visual impairment called Retinitis pigmentosa (also known as RP). The RP generally starts in the teens and progresses throughout life. Today, most diagnoses are made before adulthood, but older people still report that the diagnosis wasn’t made until later in life when the RP became severe enough to interfere with their mobility.

    Carriers of Usher Type II
    When only one USH2A gene is knocked out, half the normal amount of usherin is produced. Scientists believe that this is sufficient for normal vision and hearing, therefore no clinical symptoms result. There is nothing obvious happening to people who are carriers for Usher type 2a or 2c. However, there are theoretical reasons to think that there may be very mild hearing and vision problems that occur with older adults, but this has never been studied. It may be that these genes are partly responsible for some of the hearing vision losses that all of us have as we grow older. The story for USH2C is exactly the same.

    Hearing in Type II
    People with Usher type 2 are believed to have been born with a moderate to severe hearing loss. The hearing loss is milder in the low frequencies and more severe in the higher one. Since most speech involves the lower frequencies, this means that adults and children with Usher type 2 will usually have good oral communication skills.

    Vision in Type II
    A person with Usher 2 may become legally blind as a young adult primarily because of severe tunnel vision. While central vision often stays good for most of their lives, a few Usher 2 people will become blind as older adults.

    Balance in Type II
    The is little evidence that the vestibular function in people with Usher Type II is as effected as with Usher Type I. Therefore people with Usher Type II rarely experience balance issues related to the Usher Syndrome.

    Genes involved in Type II
    Individuals with Usher Syndrome Type II typically have a sloping congenital hearing loss that is mild to moderate in the low frequencies and severe to profound in the high frequencies. Vestibular problems are absent in Type II, which distinguishes it from Type I. RP is still present with an onset typically sometime in adolescence. Usher Type II is also further subdivided into three types which have known gene locations associated with them, USH2A, GPR98 (VLGR1)and DFNB31 (WHRN). USH2A accounts for approximately 80%, GPR98 (VLGR1) accounts for approximately 15%, and DFNB31 accounts for approximately 5% of Type 2 cases. DFNB31 mutations have also been reported in several families with recessive nonsyndromic hearing loss.

    Although these are the most common characteristics of Usher syndrome due to mutations in these genes, there can be variations. Overlapping and atypical presentations have been described for all three types of Usher syndrome. For example some mutations in USH2A can cause isolated retinitis pigmentosa without hearing loss.

    Identified disease causing mutations in all of these genes include missense, nonsense, frameshift, splice-site as well as deletions distributed across nearly all exons.

    Usher Type II subtypes
    Usher subtype 2a is by far the most common form of Usher type 2 and likely accounts for over 80% of all cases. Subtype IIc appears to be uncommon. Because the genes for 2b and 2d have not been identified, we don’t have any idea about their frequencies, but we believe them to be uncommon. There is evidence that there are more Usher II subtypes that have not been recognized.

  16. What is Usher Syndrome Type III?

    Genes involved in Type III
    Usher syndrome type III is characterized by later onset hearing loss, variable vestibular dysfunction and RP that can be present between the second and fourth decade of life. To date, only mutations in the CLRN1 (USH3A) and HARS (USH3B) genes are known to be causative for this type of Usher syndrome. Identified disease causing mutations in these genes include missense, nonsense, frameshift, splice-site as well as deletions distributed across nearly all exons.

  17. What hearing changes can occur?

    Many people with Usher syndrome are born profoundly deaf. People with profound hearing loss often get little benefit from hearing aids. Those that choose cochlear implants have very little degradation in hearing as they age since cochlear implant bypass the hair cells in the cochlear.

    The most common genetic cause of Usher syndrome, Usher Type 2a, often causes moderate to severe hearing loss at birth. Like all people, those with Usher syndrome often experience a degradation in hearing as they age. Those that may have benefited from hearing aids may find the benefit wanes as they age. Some chose to have cochlear implants to compensate for the loss. Studies show that the majority of people with Usher syndrome experience a similar rate of hearing loss with age as the general population. However, a small percentage of people with Usher Type 2 may experience a faster rate of age related hearing loss.

    People with Usher Type III often have normal hearing or a mild loss that deteriorates throughout life. By the third decade of life, most people with Usher Type III have hearing loss that is similar to all other types of Usher syndrome.

    People with Usher syndrome often greatly benefit from hearing interventions such as hearing aids and cochlear implants.

    Boys Town National Research Hospital maintains an excellent site that describes hearing loss in children. It is also applicable to adults.

  18. Glossary of Terms

    Terminology related to Usher Syndrome, blindness, hearing loss and genetics are explained or defined below.

  • Audiologist

    A person who specializes in evaluating people with hearing loss.

  • Carrier

    A person who has one unaltered version of a gene and one version with a recessive mutation. This person is not affected by the mutation.

  • Chromosome

    A structure containing many genes arranged on a long strand of DNA. Each person has 23 pairs of chromosome, including a pair of sex chromosomes.

  • Clinical geneticist

    A doctor who specializes in recognizing and treating patients with genetic diseases.

  • DNA

    Deoxyribonucleic acid. The chemical that makes up genes. It is composed of adenine (A), cytosine (C), guanine (G), and thymidine (T).

  • Gene

    A unique sequence of DNA that serves as a specific set of instructions in the body.

  • Hearing threshold

    The lowest level of sound that can be heard during a hearing test.

  • Hereditary

    Inherited; something that is passed from parent to child

  • Mutation

    A change in a gene sequence that often disrupts the function of the gene.

  • Ophthalmologist

    A doctor who specializes in studying eye diseases.

  • Otolaryngologist (ENT/ORL)

    A doctor who studies ear, nose and throat disorders.

  • Recessive mutation

    A mutation in a gene that is not strong enough to make a person affected if the person also has a normal copy of the gene.

  • Sensorineural hearing loss

    Hearing loss caused by problems in the inner ear.

  • Syndromic deafness

    Hearing loss that is associated with other medical problems.

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