The genetic forms of hearing loss are diagnosed by otologic, audiologic, and physical. Classification of hl hearing loss hl can be classified based on etiology genetic or environmental, onset. Lateonset hearing loss can be the result of noise exposure. Pdf on mar 28, 2012, nejat mahdieh and others published genetics of hearing loss find, read and cite all the research you need on researchgate.
Other symptoms may include joint or muscle pain or inflammation of the blood vessels. In many populations, approximately 50% of this hearing loss can be attributed to dfnb1, which is variable in presentation but typically characterized by congenital, nonprogressive, mild to profound sensorineural hearing loss. An overview of hereditary hearing loss karger publishers. Otosclerosis is diagnosed by health care providers who specialize in hearing. For the rare family where both sides of the family have hearing loss, it may be difficult to discern dominant from recessive hearing loss by pedigree analysis alone. A guide for patients and families harvard university.
This is a pdf file of an unedited manuscript that has. Genetic scientists categorize hearing loss into two general types. More specifically, affected people experience a reduction in hearing of greater than 30 decibels, which may occur all at once or over several days. This means that it is carried down through a family. Shl is a form of hl accompanied by additional clinical features. As such, the number of infants identified with hearing loss is likewise on the rise. It is estimated that the causes of agerelated hearing loss are 3555% genetic. Nonsyndromic hearing loss there are two types of hearing loss caused by genetics. Quite often parents are carriers of a genetic disorder and yet do not display that disorder themselves. Pdf on feb 10, 2008, ella shalit and others published genetics of hearing loss find, read and cite all the research you need on. Shl consists of hl that presents with anomalies of the eye, kidney, the musculoskeletal and the nervous systems, as well as pigmentary disorders and others 15 figure 1. Not all congenital hearing loss is genetic, and not all genetically related hearing loss is present at birth. Agerelated hearing loss genetics home reference nih.
Sometimes, knowledge of these causes can help to treat the hearing loss or stop it from getting worse. Tier i gjb2, gjb6 and mitochondrial mutation panel otoseq hearing loss panel 23 genes eya1. Their genes make them more predisposed to hearing loss due to ageing or induced by noise, drugs or infections. Genetic hearing loss hereditary hearing loss causes. Mutations in this gene cause a form of nonsyndromic hearing loss called dfnb16. The advent of hearing screening in newborns in many states has led to an increase in the use of genetic testing and related genetic services in the followup of infants with hearing loss. For many babies, the cause of hearing loss is unknown. To find literature that demonstrates the relation between hearing and balance. Nonsyndromic hearing loss and highthroughput strategies to. The hereditary hearing loss homepage aims to give an uptodate overview of the genetics of hereditary hearing impairment for researchers and clinicians working in the field this site lists data and links for all known gene localizations and identifications for monogenic nonsyndromic hearing impairment.
A combination of genetic and non genetic factors also can cause hearing loss. About 30% of people with a genetic type of hearing loss have what is called a syndromic hearing loss. A genetic change may have been inherited from further back in the family or may have occurred in that individual for the first time. Profound congenital hearing loss affects approximately 1 in infants. For example, some hearing loss may persist after stapedectomy, and in rare cases, surgery can actually worsen hearing loss. Hereditary deafness, slc26a4 gene, gene diagnosis, prenatal diagnosis, assisted reproductive technology introduction. Genetics of early childhood hearing loss the past decade has seen a continued increase in the utilization of newborn screening for hearing loss.
Understanding the genetics of deafness projects at harvard. Regulation of acting polymerization in haircells of the inner ear. One of the most common birth defects is hearing loss or deafness congenital, which can affect as many as three of every 1,000 babies born. Molecular genetic testing, possible for many types of. Although exact data is not available, it is likely that genetics plays an important role in hearing. Genetic factors make some people more susceptible to hearing loss than others. Introduction hearing loss hl is the most common sensory defect in human beings, affecting 1.
Shl accounts for 30% of hereditary hearing loss and can be inherited in an autosomal recessive, dominant and xlinked patterns. Clinical aspects of hereditary hearing loss genetics in medicine. The remaining 30% have additional signs or symptoms with over 400 different syndromes described. Approximately 30% of the genetic cases of hl are considered to be syndromic 11. The most common forms of genetic hearing loss are due to the dominant and recessive genes of which 15% is from dominant, 70% from recessive, and 15% results from other modes of. Hearing loss hl is one of the most common birth defects in developed. In most cases, hearing loss is a multifactorial disorder cau. Sensorineural hearing loss hearing loss that occurs when there is a problem in the way the inner ear or hearing nerve works. These include genetic, infectious, drugrelated, physical trauma and structural causes. Estimates of the different types of genetic deafness exceed 400, and to date, 60 genes for syndromic and nonsyndromic hearing loss have been identified. Individuals with this kind of hl may benefit only from cochlear implants 7. The non syndromic hearing loss can again inherited by. It is important to discuss any surgical procedure with an ear specialist to clarify potential risks and limitations of the operation.
Inherited genetic defects play an important role in congenital hearing loss, contributing to about 60% of deafness occurring in infants. Case report genetic characteristics of the couple with non. Genetic testing for nonsyndromic hearing loss and deafness. For recessive hearing loss, both copies of a gene must be mutated to get hearing loss. Smith abstract accurate determination of the cause of hearing loss is critically important for clinicians for prognosis and management. The major impetus behind infant screening has been the improved outcome of speech and language potential in children. Knowing the genetic basis of hearing loss provides a framework for medical management as well as. Please select some articleschapters to export citations. If, on the other hand, something is not working in the when your child is diagnosed with a hearing loss, it may be very overwhelming. Among the wellknown syndromes are usher, waardenburg and. This form of hearing loss can either be present before a child learns to speak prelingual or begin after a child learns to speak. This may be a difficult time for you and your family.
Deafness, hearing loss, genetics, genome, sequencing. It can begin as early as a persons thirties or forties and worsens gradually over time. This type of hearing loss can often be treated with medicine or surgery. Researchers have identified a few strc gene mutations in individuals with nonsyndromic hearing loss, which is loss of hearing that is not associated with other signs and symptoms. Configuration of hearing loss the configuration, or shape, of the hearing loss refers to the degree and pattern of hearing loss across frequencies tones as illustrated in a graph called an. Sudden sensorineural hearing loss genetic and rare. A child born with hearing loss of a genetic nature can have parents with normal hearing.
Cogan syndrome is a rare autoimmune disease that affects the eyes and inner ears. Conductive hearing loss hearing loss caused by something that stops sounds from getting through the outer or middle ear. Sudden sensorineural deafness is a condition that is characterized by rapid, unexplained hearing loss. All children with hearing loss 50% genetic hereditary nonsyndromic 70% 30% syndromic congenital hearing loss nonsyndromic hearing loss many different inheritance patterns autosomal recessive autosomal dominant xlinked ylinked all of these types look the same take a family history. A carrier is a person who carries one copy of a recessive mutation, but does not have hearing loss. Research suggests that people with mild symptoms of hearing loss may be twice as likely to develop dementia as those with healthy hearing. With severe or profound hl, one is considered to be deaf, when hearing loss ranges between 71 to 90 db in the former case, or profound, when the hearing loss range is above 91 db. Otof gene mutations have been inferred to be responsible for 23% nonsyndromic hearing losses nshl in some ethnic groups, and most of them meet the.
Genetics of early childhood hearing loss the facts the past decade has seen a continued increase in the utilization of newborn screening for hearing loss. The genetic forms of hearing loss are diagnosed by otologic, audiologic, and physical examination, family history, ancillary testing e. For more than half of all deaf and hard of hearing children, a genetic cause can be identified. Genetic testing for hereditary hearing loss genes is considered investigational for all other situations, including, but not limited to, testing patients without hearing loss except as addressed in related policies, e. Recognition of genetic syndromes is especially important, but this is dependent upon clear delineation of the characteristics of the syndromes. Cogans syndrome genetic and rare diseases information. The molecular genetics laboratory and the ear and hearing center offer a variety of genetic tests for patients with sensorineural hearing loss. Genetic testing is typically carried out in specific reference laboratories or university laboratories.
There are also a number of things in the environment that can cause hearing loss. On the basis of genetic testing for the couple with hearing loss, human assisted reproductive technology is a viable option to avoid the birth of infant with hereditary deafness. Depending on the age onset of hearing loss, it can cause even delay on motor development. Unconventional myosins and the genetics of hearing loss. Hearing loss occurs in 812% of those prenatally infected therefore 0. Severe to profound hearing loss abnormalities of cochlea pendred syndrome autosomal recessive usually bilateral usually prelingual nonprogressive conductive myopia vision problems sensorineural cataracts cloudiness of eye. Agerelated hearing loss also known as presbycusis is a decrease in hearing ability that happens with age. Association between hearing loss and vestibular disorders. Symptoms of the syndrome include irritation and pain in the eyes, decreased vision, hearing loss, and vertigo. By far, the more common is nonsyndromic hearing loss which includes 23 of all genetic hearing losses. Mixed hearing loss hearing loss that includes both a conductive and. In some populations about 40% of newborns with a genetic hearing loss who do not have a syndrome, have a mutation in the gjb2 gene. Another possibility is that the hearing loss is genetic.
This overview focuses on the clinical features and molecular genetics of common syndromic and nonsyndromic types of hereditary hearing loss. Hearing loss can also become apparent later in life, referred to as lateonset hearing loss. While the majority of hereditary hearing loss is not associated with a specific syndrome, many genetic syndromes possibly more than 300 are associated with congenital hearing loss, including. Find more information on genetics and hearing loss. Hearing loss is the most common sensory defect in humans, affecting normal communication in 10 percent of people aged 65 years or older. These include an otolaryngologist commonly called an ent, because they are doctors who specialize in diseases of the ears, nose, throat, and neck, an otologist a doctor who specializes in diseases of the ears, or an audiologist a health care professional trained. However, gaining a greater knowledge in this area is crucial in helping. For some of the topics, more extensive details are given in the shaded boxes. Many genes are involved in the development and function of the ear and, at the time of writing, 45 recessive, dominant and xlinked genes that cause nonsyndromic deafness have been pinpointed and another 128 loci identified positions in the genome, but where. Genetic forms of hearing loss must be distinguished from acquired non genetic causes of hearing loss. Approximately 50% of cases have a genetic cause, and 70% of these genetic cases are classified as nonsyndromic, meaning that hearing loss is the only clinical finding. Sometimes, hearing loss is due to a combination of genetic and environmen. This booklet answers many of the questions that families have about the causes of hearing loss, including genetic causes.
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