Usher syndrome is a gene mutation of various chromosomes that causes hearing-vision impairment of various degrees of severity. The most severe form, with congenital deafness and visual field loss, presents at age ten. While the partially progressive hearing impairment is treated with a hearing aid and later a chochlear implant, no therapeutic methods are yet available to treat the visual field loss. However, scientists are currently exploring the possibility of stem cell therapies and retinal implants.
What is Usher syndrome?
Usher syndrome is an inherited hearing loss caused by various chromosomal mutations. Half of the total 40 syndromes in the field of hearing vision blindness are due to Usher syndrome. The phenomenon occurs with an incidence of three to six per 100,000 cases, with most of them occurring in the sixth decade of life. The estimated number of unreported cases is probably far higher than this figure. Since Usher syndrome is often mistaken for ordinary hearing loss, while its connection with the accompanying blindness caused by the common retinal disease retinitis pigmentosa is often not recognized early enough. The first description of the syndrome goes back to Albrecht von Graefe and dates back to the 19th century, but was not sufficiently differentiated and documented at that time. The British ophthalmologist Charles Howard Usher later became the eponym of the phenomenon, as he first helped the syndrome to become known and did pioneering work in this field.
Causes
Usher syndrome is caused by several gene mutations, all of which are hereditary. Chromosome 11, chromosome 17, and chromosome 3 are particularly commonly affected by the mutation. Although clinically it is ultimately relatively irrelevant which of the chromosomes is mutated, physicians distinguish Usher syndrome into different subtypes between 1B and 3B depending on the chromosomes affected. Depending on the subtype, the form of the mutation and with it the actual cause of the phenomenon is different. Meanwhile, science assumes the existence of so-called Usher protein complexes, each of which influences the positioning of different proteins in the membrane. These proteins are thought to be involved in the signal transmission of the visual and auditory sensory cells. Thus, if one component of these complexes is missing, the entire protein complex cannot perform its actual tasks in the cell and, as a result, the respective cells degenerate. In particular, the scaffold protein harmonin of Usher subtype 1C is thought to play an important role in this regard.
Symptoms, complaints, and signs
Usually, Usher syndrome manifests early in life as sensorineural hearing loss due to damage to hair cells in the cochlea. Less commonly than mere hearing loss, complete deafness is present from birth. In addition to these early symptoms, retinopathy pigmentosa is one of the later-onset manifestations of Usher syndrome. In this disease, photoreceptors from the periphery to the macula die off bit by bit. At first, night blindness appears. Later, the visual field is reduced and the so-called tunnel vision develops. Depending on the subtype, this phenomenon can lead to complete blindness. In some cases, these symptoms are additionally accompanied by epileptic seizures.
Diagnosis and course of the disease
The physician makes the diagnosis of Usher syndrome using various diagnostic procedures. The earliest possible diagnosis is crucial because otherwise the patient will not have time to adjust psychologically and physically to the subsequent loss of sensory perception and possibly prepare by learning new communication procedures. In addition to an electroretinogram, a DNA chip, protein chip or genetic analysis may take place. The course of the disease depends greatly on the type. In terms of the severity of the disease, three types can be distinguished. Usher type 1 (USH1) corresponds to the most severe course of the disease, in which deafness and, in some cases, a disturbed sense of balance are present from birth. Already from the age of ten, this subtype shows the onset of retinopathia pigmentosa. Usher type 2 (USH2) is defined by constant, profound hearing loss, with the onset of retinopathia pigmentosa during puberty.In Usher type 3 (USH3), progressive hearing loss and visual field loss do not begin until the second half of life.
Complications
Due to Usher syndrome, affected individuals suffer from very severe complaints and symptoms. As a rule, hearing loss occurs at a very young age. Especially young people suffer from psychological complaints or even depression. In the further course it finally comes to a complete hearing loss and thus to clear restrictions in the everyday life. In children, Usher syndrome also leads to delayed and very limited development. Furthermore, the disease can also lead to night blindness. In rare cases, those affected suffer from complete blindness. The syndrome also leads to epileptic seizures, which are associated with very severe pain. In the worst case, these can also lead to the death of the affected person. Due to the symptoms, many patients are dependent on the help of other people in their daily lives and are unable to cope with everyday life on their own. With the help of various therapies, some complaints can be alleviated. However, the progressive course of the disease cannot be limited. Patients are dependent on hearing aids and visual aids in their daily lives. However, life expectancy is not altered by Usher syndrome.
When should you see a doctor?
Since Usher syndrome cannot heal itself, the affected person is dependent on a visit to a doctor. This is the only way to prevent further complications or discomfort, which can make the affected person’s life much more difficult. Since it is a genetic disease, it cannot be completely cured. However, if a child is desired, genetic counseling can be performed to prevent Usher syndrome from recurring in the descendants. A doctor should be consulted for this disease if the affected child suffers from complete deafness. This has been present since birth. Furthermore, there are also complaints of the eyes, which also become stronger with increasing age. The patients also suffer from night blindness, which can also indicate the syndrome. In some cases, Usher syndrome is manifested by epileptic seizures. If such a seizure occurs, an emergency physician should be called immediately or a hospital should be visited directly. The syndrome itself can be detected by a general practitioner or by a pediatrician. Further treatment depends on the severity of the symptoms and is carried out by a specialist. Usually, the life expectancy of the patient is not reduced by this syndrome.
Treatment and therapy
There is no treatment for the retinopathia pigmentosa of Usher syndrome in particular to date. However, gene therapy approaches are currently under investigation and should soon allow replacement of defective genes in the retina. In addition, therapeutic options such as stem cell therapies and retinal implants are also currently being explored. The hearing impairment of Usher syndrome is treated with a hearing aid and may require a cochlear implant in later stages. Usually, Usher syndrome patients learn sign language at an early age. If severe visual field impairments occur or exist, tactile sign language can be learned to preserve the ability to communicate. This involves taking the other person’s hands in one’s own and feeling the respective signs.
Prevention
Because Usher syndrome is a hereditary disorder based on a gene mutation, the condition cannot be prevented. However, because early diagnosis is important in this disorder, regular monitoring of one’s hearing and visual field qualities is at least one measure that can increase one’s ability to adapt to changing conditions through early diagnosis.
Follow-up
Usher syndrome is a gene mutation of various chromosomes that is usually associated with hearing loss and severe visual impairment. Affected individuals must wear hearing aids, and in cases of very severe hearing loss, a cochlear implant may help. For a patient who has had Usher syndrome since birth, everyday life is usually easier to cope with. Patients who only become deaf in the course of their lives and eventually go blind often find dealing with the disease much more problematic. Their everyday life is suddenly very restricted and burdened.It is therefore very important to have the support of acquaintances, friends, specialists and appropriate therapists. With optimal treatment, it is often possible for the affected person to lead a largely normal life. Of course, help in everyday life is still necessary: The affected person’s home must be equipped to meet the needs of the disabled. If the patient pursues a profession, this must correspond to his physical possibilities and the workplace should be adapted to his disability. Contact with other people should be ensured so that affected persons do not withdraw completely. Communication can take place via lip reading or sign languages. If the blindness increases in the course of the disease, it is also possible to communicate via so-called tactile sign language, corresponding signs are conveyed via physical contact. A competent contact point for those affected is offered by the Usher Syndrome Association.
What you can do yourself
Usher syndrome requires medical treatment. Affected people must wear a hearing aid or, in the case of severe hearing loss, an implant to improve hearing. People who have had Usher syndrome from birth usually have an easier time. For patients who only become deaf and eventually blind in the course of their lives, the sudden limitations represent a major burden in everyday life. It is therefore important to have good support from friends, acquaintances and specialists as well as therapists. Then the patient can be given the best possible treatment, which allows him or her to lead a comparatively normal life. Nevertheless, people who are deaf and blind are dependent on support in everyday life. The home must be equipped to meet the needs of the handicapped and the job must correspond to the person’s physical abilities. Affected persons should learn lip-reading and other techniques at an early stage in order to be able to communicate better with other people in everyday life. With increasing blindness, it is also possible to communicate using so-called tactile sign language. Possible languages include Tadoma or Gestuno, the latter focusing on feeling the signs through physical contact. The Usher-Syndrom e. V. association provides further points of contact for those affected.
