Generally, the younger the person is with a hearing impairment, the more likely it was down to genetic factors, disease or physical abnormality. Hearing loss genetic centers in michigan childrens hospital of michigan dmc detroit medical center genetic and metabolic disorders 38329330 c. Their genes make them more predisposed to hearing loss due to ageing or induced by noise, drugs or infections. Sensorineural hearing loss snhl is the most common sensory disorder. For more than half of all deaf and hard of hearing children. There are also a number of things in the environment that can cause hearing loss. This renders noiseinduced hearing loss nihl one of the most important occupational health hazards.
Several factors including infections, noiseexposure, ototoxic medications or genetic disorders could cause hearing impairment. Pdf instructions for taking a pedigree author notes. Deafness and hereditary hearing loss, nonsyndromic breda. Beside agerelated hearing loss, nihl is the second most frequent form of hearing loss. Hearing loss can also become apparent later in life, referred to as lateonset hearing loss. Hereditary deafness is one of the most genetically heterogeneous conditions known to date. Home test catalog by test az hearing loss panel hearing loss panel forms and documents. As you work to identify the cause of your childs hearing loss, it will be helpful to have a basic understanding of genetics and the major categories of inheritance. Hearing loss identified by newborn screening can prompt an early investigation into the etiology of the loss. The genetics of hearing loss can be complicated and difficult to understand. Agerelated hearing loss genetics home reference nih. 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. The genetic forms of hearing loss are diagnosed by otologic, audiologic, and physical examination, family history, ancillary testing e.
In contrast, syndromic hearing loss occurs with signs and symptoms affecting other parts of the body. Pdf on feb 10, 2008, ella shalit and others published genetics of hearing loss find, read and cite all the research you need on. For patients and families genetic testing for hearing loss. A genetic hearing loss may be inherited in an autosomal dominant, autosomal recessive, or xlinked mendelian manner, or through the maternal lineage by mitochondrial inheritance. Friedman is the chief of the laboratory of molecular genetics, national institute on deafness and other communication disorders, national institutes of health. In the case of hearing loss, variations in a large number of different genes can lead to hearing loss by altering the ability of the inner ear to function properly. This overview focuses on the clinical features and molecular genetics of common syndromic and nonsyndromic types of hereditary hearing loss. Most cases of hearing loss detected by newborn screening have a genetic etiology. Genetics and hearing loss perspectives on hearing and. A specific etiology can be identified in close to 90% of the cases. The major impetus behind infant screening has been the improved outcome of speech and language potential in children. Genes associated with hearing loss are often called hearing loss genes. Agerelated hearing loss also known as presbycusis is a decrease in hearing ability that happens with age.
Genetic factors make some people more susceptible to hearing loss than others. A survey of early hearing detection and intervention programs sarah k. Genes are passed from parents to children and cause things to run in families. Gene therapy for hearing loss human molecular genetics. Gene therapy, or the treatment of human disease using genetic material, for inner ear dysfunction is coming of age. Genetics and hearing loss cs mott childrens hospital. Molecular genetic testing, possible for many types of. It can begin as early as a persons thirties or forties and worsens gradually over time. More than 400 syndromes have been identified with hearing loss as a symptom mutations in certain genes cause sensitivity to specific antibiotics that, if used causes hearing loss in affected individuals. Hearing loss can be caused by changes in genes or by outside factors like injuries, illness or certain medications, or both. 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. Understanding the genetics of deafness projects at harvard.
It is a complex condition that is influenced by both environmental factors and genetic factors. Hearing loss is the most common sensory defect in humans, affecting normal communication in 10 percent of people aged 65 years or older. It has been estimated that at least 1% of human genes may be involved in the pathogenesis of some form of hereditary hearing loss. These tests identify approximately 80 percent of the genetic causes of hearing loss in children with bilateral snhl.
Although exact data is not available, it is likely that genetics plays an important role in hearing loss in the. Quite often parents are carriers of a genetic disorder and yet do not display that disorder themselves. One common way is by the conditions pattern of inheritance. Hearing impairment, particularly nonsyndromic hearing loss, affects multiple families across the world. Genetics evaluation guidelines for the etiologic diagnosis. Genetic hearing loss may be linked to health or learning problems. Unconventional myosins and the genetics of hearing loss. Genedx is a world leader in genomics with an acknowledged expertise in rare and ultrarare genetic disorders, as well as an unparalleled comprehensive genetic testing menu. A genetics evaluation can provide the family and providers with several critical pieces of information. A carrier is a person who carries one copy of a recessive mutation, but does not have hearing loss. Genetics of early childhood hearing loss the past decade has seen a continued increase in the utilization of newborn screening for hearing loss.
Even if ones hearing loss is down to old age though genetic factors are still at play here. Bronya keats, is professor and chair of the department of genetics and director of the molecular and human genetics center at louisiana state university health sciences center. 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. For several genetic subtypes of deafness the locus has been mapped on a defined chromosomal region, yet the gene remains. For recessive hearing loss, both copies of a gene must be mutated to get hearing loss. Functional variants in known hearing impairment genes. Genetics and hearing loss hearing loss association of. A child born with hearing loss of a genetic nature can have parents with normal hearing. Lateonset hearing loss can be the result of noise exposure. In males, hearing loss is prelingual and rang e from sever e to prof ound while in females hearing loss is. To learn more about genetic causes of hearing loss, you may download. Hearing loss can occur because of damage to the ear, especially the inner ear. Clinical aspects of hereditary hearing loss genetics in.
Rudman, left, is the clinical chief resident at the university of miami department of otolaryngologyhead and neck surgery. Staff of this laboratory ascertain families with hearing loss, map and identify the responsible genes and study their function in the auditory system. Genetic hearing loss hereditary hearing loss causes. Permanent hearing loss at birth or in early childhood is common and has many genetic and environmental. About 1 in 500 infants is born with or develops hearing loss.
The gene encoding connexin 26 cx26 is known to be the main cause for most recessive gene hearing loss. The main intent of genetic testing for a child who is deaf or hard of hearing is optimal care and management, precision medicine, for that child. Herein, we describe stateoftheart research on genetic hearing loss treatment through gene therapy and discuss the obstacles to overcome in curative treatments. Nonsyndromic hearing loss genetics home reference nih. When a child is born with hearing loss or develops hearing loss early in childhood, over 50% of the time the cause is genetic and due to a genetic change, or mutation. While successful translation of this progress into treatments for humans awaits, there is growing interest from patients, scientists. This booklet is designed to help explain the role of genetics in hearing loss, how genetic testing is done, what the results of genetic tests mean, and what options are available for treatment and counseling. Potential treatments for genetic hearing loss in humans nature.
Inherited genetic defects play an important role in congenital hearing loss, contributing to about 60% of deafness occurring in infants. It is estimated that the causes of agerelated hearing loss are 3555% genetic. A guide for patients and families understanding the genetics of deafness this booklet was created by. Its underlying etiologies include a broad spectrum of genetic and environmental factors that can lead to hearing loss that is congenital or late onset, stable or progressive, drug related, noise induced, age related, traumatic or postinfectious. A guide for patients and families harvard university. As such, the number of infants identified with hearing loss is likewise on the rise.
Tier i and otoseq testing are indicated for any patient with sensorineural hearing loss of unknown etiology. 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 inheritance. Tier i testing includes analysis for mutations in gjb2, gjb6, 12s rrna and trnaser ucn. Associate director, harvard medical school center for hereditary deafness. Many parents are unfamiliar with how hearing loss could be caused by genetic factors. Nonsyndromic hearing loss can be classified in several different ways. Genes can cause hearing loss in many different ways. For many children with hearing loss, the cause is unknown.
Genetic mutations in over 100 genes can cause congenital nonsyndromic and syndromic hearing loss. Overall, the amount of different genetic data presented here variants with earlyonset and lateonset hearing loss in addition to genetic association with normal hearing function, together with relevant functional evidence. Introduction hearing loss hl is the most common sensory defect in human beings, affecting 1. In most cases, hearing loss is a multifactorial disorder cau. Nonsyndromic hearing loss is a partial or total loss of hearing that is not associated with other signs and symptoms. The majority of children with genetic hearing loss do not have any other birth defects or major health concerns associated with their hearing loss. Recent progress in developing gene therapy treatments for genetic hearing loss has demonstrated tantalizing proofofprinciple in animal models. Genetic determinants of nonsyndromic hearing impairment.