Congenital hearing loss: diagnostic and management in otological aspects (original) (raw)
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Hearing loss: A review on molecular genetics and epidemiologic aspects
2017
Background and aims: Hearing loss (HL) happens due to the genetic or environmental causes or both. Risk factors include congenital infections and congenital deformities of auricle and ear duct. The present study was performed to briefly explain the genetics, molecular biology and epidemiology of HL in Middle East especially in Iran. Methods: An intense an comprehensive literature search was prformed through heading journals in the field. All data was organized using Mendeley software and incorporated to the text as required. Results: While the etiology of 25% of HL cases remains indistinct, it is estimated that at least 50% of pre lingual HL cases have a genetic cause. About 70% of genetic HL cases are non Syndromic (NSHL) without anomaly, whereas the remaining 30% are Syndromic. Autosomal recessive non-syndromic hearing loss forms (ARNSHL) are the severest forms of congenital HL with defect in cochlea. In addition to X-linked (DFNX), autosomal dominant (DFNA), autosomal recessive (...
Genetic syndromes involving hearing
International Journal of Pediatric Otorhinolaryngology, 2009
The fundamental processes involved in the mechanism of hearing seem to be controlled by hundreds of genes and hereditary hearing impairment may be caused by a large variety of genetic mutations in different genes. Approximately 150 loci for monogenic syndromic and non-syndromic hearing impairment (HI) disorders have been mapped to the human genome. The identification of these genes and functional analysis of the proteins they encode, are paving the way towards a better understanding of the physiology and pathophysiology of the auditory system. To date, approximately 50 causative genes have been identified. Methods: The clinical and neuroradioldical findings of syndromal hearing impairment are analysed. Results: This paper presents an updated report on genetic syndromes in which a hearing impairment is involved, with a particular attention to the ones associated with external ear and craniofacial malformations. Conclusions: Concepts in human genetics are rapidly evolving together with technologies. The concept itself of gene is changing. A genetic diagnosis of syndromal hearing impairment has many practical consequences: it can implies specific prognosis, specific management, specific recurrence risk in relatives and, if the diagnosis is confirmed at the molecular level, possibility of a specific early prenatal diagnosis for severe syndromes. It is important to highlight the necessity that the pediatric otolaryngologist must have a close collaboration with a clinical geneticist and a neuroradiologist.
Genetics of non syndromic hearing loss
Medical Journal Armed Forces India, 2015
There are several reasons why both doctors and patients need to understand the genetics related to NSHL. Firstly, the aetiology of the NSHL can be explained to the patient. The patient then is aware of the cause for the hearing m e d i c a l j o u r n a l a r m e d f o r c e s i n d i a 7 1 (2 0 1 5) 3 6 3-3 6 8
First-Line Molecular Genetic Evaluation of Autosomal Recessive Non-Syndromic Hearing Loss
Turkish Archives of Otorhinolaryngology, 2019
Objective: The aim of this study is to in vestigate the efficiency of a first-line molecular genet ic evaluation approach, in children with deafness. Methods: Patients who were found to have sensorineural hearing loss by age-appropriate audiological tests were selected for the molecular genetic evaluation. The molecular genetic evaluation was carried out with GJB2 gene sequence analysis and mtDNA m.1555A>G mutation Restriction Fragment Length Polymorphism (RFLP) analysis. Additionally, in a small group of patients, hearing loss Multiplex Ligation-dependent Probe Amplification (MLPA) analysis was done out to identify the possible role of copy number changes. Results: In this Turkish cohort, which included 104 index patients and 78 relatives, 33 (31.7%) had Pathogenic/Likely Pathogenic variants. One or more GJB2 sequence variants were identified in 46 (44.1%) of the 104 index patients. The homozygous c.35delG mutation by itself explained the etiology in 24% of our ARSNHL group. In one (5%) of the 20 patients of MLPA group, a hemizygous deletion in POU3F4 gene was detected. Conclusion: In our Turkish cohort, we applied a first-line molecular genetic evaluation approach using GJB2 gene sequence analysis and mtDNA m.1555A>G RFLP analysis. This approach revealed the genetic etiology of 44.1% of our index patients. Additionaly, the results of hearing loss MLPA analysis revealed the limited role of copy number changes in this patient group. Furthermore, with a detailed genotype-phenotype association workup, 2 rare cases of Deafness with Palmoplantar Hyperkeratosis and Keratitis-Ichthyosis-Deafness syndrome were reported.
Genetics Evaluation Guidelines for the Etiologic Diagnosis of Congenital Hearing Loss
Genetics in Medicine, 2002
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 follow-up of infants with hearing loss. A significant proportion of those with congenital hearing loss have genetic etiologies underlying their hearing loss. To ensure that those identified with congenital hearing loss receive the genetic services appropriate to their conditions, the Maternal and Child Health Bureau of the Health Resources and Services Administration funded the American College of Medical Genetics to convene an expert panel to develop guidelines for the genetic evaluation of congential hearing loss. After a brief overview of the current knowledge of hearing loss, newborn screening, and newborn hearing screening, we provide an overview of genetic services and a guideline that describes how best to ensure that patients receive appropriate genetic services. The significant contribution of genetic factors to these conditions combined with the rapid evolution of knowledge about the genetics of these conditions overlaid with the inherently multidisciplinary nature of genetic services provides an example of a condition for which a well-integrated multidisciplinary approach to care is clearly needed.
Research of genetic bases of hereditary non-syndromic hearing loss
Turk pediatri arsivi, 2017
Hearing loss is the most common sensory disorder that affects approximately one per 1000 live births. With this project, we aimed to identify gene variants that were common causes of hearing loss in Turkey to contribute to the planning of genetic screening programs for hearing loss, as well as to improve genetic counseling to affected families. Twenty-one families with at least two affected individuals and parental consanguinity who presented with non-syndromic severe-to-profound sensorineural hearing loss were included in this study. We first screened for mutations in GJB2 and mitochondrial DNA 12S RNA genes. Subsequently, we genotyped the TMIE c.250C>T and SNP markers flanking the SLC26A4, MYO7A, MYO15A, OTOF, CDH23, TMIE, TECTA, PCDH15, TMC1, TMPRSS3, TMHS genes in the remaining twelve families without mutations in GJB2. Screening for mutations in GJB2 gene showed c.[35delG];[35delG] mutation in four families, c.[35delG];[507C>A] mutation in two families, c.[35delG];[-23+1G...
2017
More than 50% of congenital sensorineural hearing loss and deafness cases have a genetic (hereditary) cause. As can be seen from the above, a significant clinical polymorphism of many hereditary syndromic and nonsyndromic forms of sensorineural hearing loss is primarily conditioned by the genetic heterogeneity of the auditory perception pathology, due to the complex structural and functional organization of the auditory analyzer. The description of the syndromic and nonsyndromic forms of sensorineural hearing loss is represented by the known syndromes as described above.
Autosomal recessive nonsyndromic deafness locus DFNB63 at chromosome 11q13.2–q13.3
Human Genetics, 2007
A genome wide linkage analysis of nonsyndromic deafness segregating in a consanguineous Pakistani family (PKDF537) was used to identify DFNB63, a new locus for congenital profound sensorineural hearing loss. A maximum two-point lod score of 6.98 at θ = 0 was obtained for marker D11S1337 (68.55 cM). Genotyping of 550 families revealed three additional families (PKDF295, PKDF702 and PKDF817) segregating hearing loss linked to chromosome 11q13.2-q13.3. Meiotic recombination events in these four families define a critical interval of 4.81 cM bounded by markers D11S4113 (68.01 cM) and D11S4162 (72.82 cM), and SHANK2, FGF-3, TPCN2 and CTTN are among the candidate genes in this interval. Positional identification of this deafness gene should reveal a protein necessary for normal development and/or function of the auditory system.
The Genetic Basis of Hearing Loss: Recent Advances and Future Prospects
International Journal of Head and Neck Surgery
Hearing loss (HL) is a common and complex condition that can occur at any age, be inherited or acquired, and is associated with a wide number of etiologies. HL is the most common sensory deficit in newborn children. In developed countries, genetic causes are considered the most frequent etiology of HL, and are estimated to account for 75% of the causes of HL. Current estimates suggest 1% of human genes (200-250 genes) are associated with genetic HL, and to date, more than 80 genes with over 1000 mutations and 140 loci have been identified associated with non-syndromic HL. The Online Mendelian Inheritance in Man reports more than 400 syndromes with HL. Syndromic and non-syndromic HL can be caused by different mutations within the same gene. Establishing the genetic cause of HL in prelingual children facilitates the medical course of action, rehabilitation choices and long term care in children. Patients with HL of undiagnosed etiology should be evaluated by a clinical geneticist and consider genetic testing as a part of their multidisciplinary evaluation.