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1.
Article in Chinese | WPRIM | ID: wpr-922018

ABSTRACT

OBJECTIVE@#To detect common pathogenic variants associated with congenital deafness among neonates from Huizhou and surrounding areas and discuss its implications.@*METHODS@#Thirteen hot-spot mutations in four most common pathogenic genes were screened among 20 934 neonates from March 2017 to December 2019.@*RESULTS@#In total 760 neonates were found to carry common pathogenic variants (3.63%). Sixty two neonates have carried homozygous/compound heterozygous variants or homoplasmy/heteroplasmy mutations of mtDNA (0.29%). Further analysis of five abnormal cases revealed that 3 of them have carried compound heterozygous mutations of GJB2 gene, and 2 were due to compound heterozygous variants of the CDH23 gene.@*CONCLUSION@#Genetic testing has a great clinical significance for the prevention and reduction of congenital hearing loss, but the scope needs to be updated and redefined by removing mutation sites with a very low rate, adding new significant sites, and improvement of the technical strategies.


Subject(s)
Connexin 26 , Connexins/genetics , DNA Mutational Analysis , Deafness/genetics , Genetic Testing , Hearing Loss/genetics , Humans , Infant, Newborn , Mutation , Neonatal Screening
2.
Article in Chinese | WPRIM | ID: wpr-921967

ABSTRACT

ABCC1 gene is expressed in various tissues and organs of the human body, and can transport substrates including drugs, heavy metals, toxic substances and organic anions. Previous research on ABCC1 gene has mostly focused on tumor multidrug resistance. Recently, ABCC1 has been proposed as a candidate gene for hereditary hearing impairment, which has attracted much attention. ABCC1-associated deafness may be related to its role in biological barriers. This article has summarized recent progress in the study of the role of ABCC1 in the blood-testis barrier, placental barrier, blood-brain barrier, blood-labyrinth barrier, which may provide insight into its biological functions.


Subject(s)
Biological Transport , Deafness/genetics , Female , Humans , Male , Multidrug Resistance-Associated Proteins/genetics , Placenta , Pregnancy
3.
Article in Chinese | WPRIM | ID: wpr-888364

ABSTRACT

OBJECTIVE@#To explore the genetic basis of a Chinese pedigree affected with progressive non-syndromic sensorineural hearing loss.@*METHODS@#High-throughput DNA sequencing was carried out to analyze 415 genes associated with hereditary deafness in the proband. Sanger sequencing was carried out to verify the suspected variants among her family members.@*RESULTS@#The proband was found to carry a heterozygous c.842T>A (p.Ile281Asn) variant of the POU4F3 gene. The same variant was found among all other patients from the pedigree including the proband's mother, brother, aunt and maternal grandfather, but not among those with normal hearing. Based on the standards and guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology, the c.842T>A(p.Ile281Asn) variant of the POU4F3 gene was predicted as likely pathogenic (PM2+PM5+PP1+PP3+PP4).@*CONCLUSION@#A Chinese pedigree affected by a rare type autosomal dominant deafness-15 (DFNA15) due to a novel c.842T>A (p.Ile281Asn) variant of the POU4F3 gene was identified. The result has facilitated genetic counseling and risk assessment for the pedigree.


Subject(s)
China , Deafness/genetics , Female , Genetic Testing , Hearing Loss, Sensorineural/genetics , Humans , Male , Mutation , Pedigree
4.
Article in Chinese | WPRIM | ID: wpr-879601

ABSTRACT

OBJECTIVE@#To explore the genetic basis for a Chinese pedigree affected with non-syndromic hearing loss (NSHL).@*METHODS@#Commercialized gene chip was applied to detect common mutations associated with congenital deafness. Whole exome sequencing was carried out for patients for whom gene chip yielded a negative result. Candidate variants were verified by Sanger sequencing.@*RESULTS@#Two patients from the pedigree were discovered to carry compound heterozygous variants of the TRIOBP gene, namely c.3299C>A and c.5185-2A>G. Their parents had normal hearing and were both heterozygous carriers of the above variants. Both variants had co-segregated with the disease phenotype in the pedigree and were unreported previously.@*CONCLUSION@#Pathogenic variants of the TRIOBP gene comprise an important factor for NSHL. The novel c.5185-2A>G and c.3299C>A variants discovered in this study have enriched the mutational spectrum of the TRIOBP gene and enabled molecular diagnosis and genetic counseling for the family.


Subject(s)
Deafness/genetics , Hearing Loss, Sensorineural/genetics , Heterozygote , Humans , Microfilament Proteins/genetics , Mutation , Pedigree , Whole Exome Sequencing
5.
Article in Chinese | WPRIM | ID: wpr-879518

ABSTRACT

OBJECTIVE@#To explore the genetic basis of four Chinese families affected with deafness.@*METHODS@#All probands were subjected to next generation sequencing (NGS). Suspected variant were verified by Sanger sequencing among the family members. Prenatal diagnosis was provided for three couples through Sanger sequencing.@*RESULTS@#All probands were found to carry pathogenic variants of the TMC1 gene, which included c.100C>T (p.R34X) and c.642+4A>C in family 1, c.582G>A (p.W194X) and c.589G>A (p.G197R) in family 2, c.1396_1398delAAC and c.1571T>C (p.F524S) in family 3, and homozygosity of c.2050G>C (p.D684H) in family 4. All parents were heterozygous carriers of the variants. The c.642+4A>C and c.1571T>C (p.F524S) were unreported previously. Prenatal diagnosis revealed that none of the fetuses were affected. Follow-up confirmed that all newborns had normal hearing.@*CONCLUSION@#Variant of the TMC1 gene probably underlay the deafness in the four families. Above findings have enhanced our understanding of the function of the TMC1 gene and enriched its variant spectrum. The results also facilitated genetic counseling and prenatal diagnosis for the families.


Subject(s)
China , Deafness/genetics , Female , Genetic Variation , Humans , Infant, Newborn , Male , Membrane Proteins/genetics , Mutation , Pedigree , Pregnancy , Prenatal Diagnosis
6.
Article in Chinese | WPRIM | ID: wpr-879517

ABSTRACT

OBJECTIVE@#To analyze the results of concurrent hearing and deafness genetic screening and follow up of newborns.@*METHODS@#In total 33 911 babies born to 5 designated hospitals in Nanshan District of Shenzhen city from October 2017 to December 2019 were included. All subjects underwent concurrent hearing and deafness genetic screening covering 21 variants of 4 genes including GJB2, SLC26A4, GJB3 and Mt12SrRNA. For those with positive results, Sanger sequencing was carried out for confirmation.@*RESULTS@#93.32% subjects passed the first-round hearing screening, and 87.01% passed the recheck testing. The overall detection rate was 4.18%. The detection rates for GJB2, SLC26A4, GJB3 and Mt12srRNA variants were 1.98%, 1.58%, 0.37% and 0.25%, respectively. 126 and 84 subjects were found with high risk for delayed-onset and drug-induced hearing loss, respectively. In addition, 4 and 5 subjects were found to harbor homozygous/compound heterozygous variants of the GJB2 and SLC26A4 genes, respectively. Concurrent screening showed that subjects (with heterozygous variants) who did not passed the two round hearing test were as follows: GJB2 with 6.75% in the first round and 2.61% in the second round testing, SLC26A4 (3.3%/1.2%), GJB3 (0.72%/0.14%) and 12SrRNA (0.36%/Nil), respectively. Moreover, the No-pass rate in the subjects with homozygous or compound variants in single gene, heterozygous variant in single gene, heterozygous variant in multiple genes, and homozygous variant in GJB3 gene were significantly higher than the subjects with negative results of genetic screening.@*CONCLUSION@#Concurrent newborn genetic screening can enhance the effectiveness of hearing screening and enable earlier identification and intervention for children with hearing impairment. Follow-up can improve the diagnostic rate for children who are positive for the concurrent screening. Nevertheless, genetic and hearing screening cannot replace the diagnostic testing. It is necessary to conduct comprehensive analysis for the results of genetic and hearing screening and radiological examinations. Sanger sequencing and next-generation sequencing are critical for ascertain the diagnosis.


Subject(s)
China/epidemiology , DNA Mutational Analysis , Deafness/genetics , Follow-Up Studies , Genes/genetics , Genetic Testing/statistics & numerical data , Hearing/genetics , Hearing Tests/statistics & numerical data , Humans , Infant, Newborn , Mutation , Neonatal Screening
7.
Article in Chinese | WPRIM | ID: wpr-879469

ABSTRACT

OBJECTIVE@#To detect additional variants for newborn carriers of single heterozygous variants of the GJB2 or SLC26A4 gene by genechip analysis in Changsha area, and explore the variation spectrum of deafness-related genes in this region.@*METHODS@#For 462 newborns carrying single heterozygous variants of the GJB2 or SLC26A4 gene, all exons of the genes were subjected to Sanger sequencing. The pathogenicity of the variants was analyzed by database and literature search.@*RESULTS@#For 305 newborns carrying a heterozygous GJB2 variant, 143 (46.49%) were found to carry additional variants, including 29 (9.51%) with c.109G>A likely pathogenic variant, and 1 (6.48%) with c.551G>A pathogenic variant. Among 153 newborns carrying single heterozygous variant of the SLC26A4 gene, 2 (1.31%) were found with a c.281C>T variant, and 1 (0.65%) with a c.1547_1548ins pathogenic variant. Among 4 newborns simultaneously carrying GJB2 and SLC26A4 variants, two were found to carry c.109G>A and c.844T>C variants (clinical significance unknown), respectively.@*CONCLUSION@#For newborns carrying single heterozygous variants of the GJB2 or SLC26A4 gene by genechip analysis, the detection rate for other variants is quite high. Sanger sequencing can significantly improve the detection rate of high-risk newborns and enrich the variant spectrum of deafness genes.


Subject(s)
Connexins/genetics , DNA Mutational Analysis , Deafness/genetics , Genetic Carrier Screening , Heterozygote , Humans , Infant, Newborn , Mutation , Oligonucleotide Array Sequence Analysis , Sulfate Transporters/genetics
8.
Braz. j. otorhinolaryngol. (Impr.) ; 85(1): 92-98, Jan.-Feb. 2019. tab
Article in English | LILACS | ID: biblio-984045

ABSTRACT

Abstract Introduction: In different parts of the world, mutations in the GJB2 gene are associated with nonsyndromic hearing loss, and the homozygous 35delG mutation (p.Gly12Valfs*2) is a major cause of hereditary hearing loss. However, the 35delG mutation is not equally prevalent across ethnicities, making it important to study other mutations, especially in multiethnic countries such as Brazil. Objective: This study aimed to identify different mutations in the GJB2 gene in patients with severe to profound nonsyndromic sensorineural hearing loss of putative genetic origin, and who were negative or heterozygote for the 35delG mutation. Methods: Observational study that analyzed 100 ethnically characterized Brazilian patients with nonsyndromic severe to profound sensorineural hearing loss, who were negative or heterozygote for the 35delG mutation. GJB2 mutations were detected by DNA-based sequencing in this population. Participants' ethnicities were identified as Latin European, Non-Latin European, Jewish, Native, Turkish, Afro-American, Asian and Others. Results: Sixteen participants were heterozygote for the 35delG mutation; 14 participants, including three 35delG heterozygote's, had nine different alterations in the GJB2 gene. One variant, p.Ser199Glnfs*9, detected in two participants, was previously unreported. Three variants were pathogenic (p.Trp172*, p.Val167Met, and p.Arg75Trp), two were non-pathogenic (p.Val27Ile and p.Ile196Thr), and three variants were indeterminate (p.Met34Thr, p.Arg127Leu, and p.Lys168Arg). Three cases of compound heterozygosity were detected: p.[(Gly12Valfs*2)];[(Trp172*)], p.[(Gly12Valfs*2)](;)[(Met34Thr)], and p.[(Gly12Valfs*2)(;)[(Ser199Glnfs*9)]). Conclusion: This study detected previously unclassified variants and one case of previously unreported compound heterozygosity.


Resumo Introdução: Em diferentes partes do mundo, mutações do gene GJB2 estão associadas a perda auditiva não sindrômica e a mutação homozigótica 35delG (p.Gly12Valfs*2) é uma das principais causas de perda auditiva hereditária. No entanto, a mutação 35delG não é igualmente prevalente em todas as etnias, faz com que seja importante estudar outras mutações, especialmente em países multiétnicos, como o Brasil. Objetivo: Identificar diferentes mutações no gene GJB2 em pacientes com perda auditiva neurossensorial grave ou profunda não sindrômica de origem genética putativa e negativos ou heterozigotos para a mutação 35delG. Método: Estudo observacional que analisou 100 pacientes brasileiros caracterizados etnicamente, com perda auditiva neurossensorial grave ou profunda não sindrômica, negativos ou heterozigotos para a mutação 35delG. As mutações de GJB2 foram detectadas por sequenciamento baseado no DNA nessa população. As etnias dos participantes foram identificadas como latino-europeia, não latino-europeia, judaica, nativa, turca, negra, asiática e outras. Resultados: Dezesseis participantes eram heterozigotos para a mutação 35delG e 14, incluindo três heterozigotos para 35delG, apresentaram nove alterações no gene GJB2. Uma variante, p.Ser199Glnfs*9, detectada em dois participantes, não havia sido relatada anteriormente. Três variantes eram patogênicas (p.Trp172*, p.Val167Met, e p.Arg75Trp), duas não patogênicas (p.Val27Ile e p.Ile196Thr) e três indeterminadas (p.Met34Thr, p.Arg127Leu, e p.Lys168Arg). Três casos de heterozigosidade composta foram detectados: p.[(Gly12Valfs*2)];[(Trp172*)], p.[(Gly12Valfs*2)](;)[(Met34Thr)], e p.[(Gly12Valfs*2)(;)[(Ser199Glnfs*9)]). Conclusão: Este estudo detectou variantes não classificadas anteriormente e um caso de heterozigosidade composta ainda não relatada.


Subject(s)
Humans , Male , Female , Child, Preschool , Child , Adolescent , Adult , Middle Aged , Young Adult , Connexins/genetics , Hearing Loss, Sensorineural/ethnology , Hearing Loss, Sensorineural/genetics , Mutation , Severity of Illness Index , Brazil/ethnology , Deafness/ethnology , Deafness/genetics , Gene Frequency , Hearing Loss, Sensorineural/congenital
9.
Int. arch. otorhinolaryngol. (Impr.) ; 19(4): 359-363, Oct.-Dec. 2015. tab, ilus
Article in English | LILACS | ID: lil-768337

ABSTRACT

Introduction Large vestibular aqueduct syndrome (LVAS) is characterized by the enlargement of the vestibular aqueduct associated with sensorineural hearing loss. It is the most common radiographically detectable inner ear anomaly in congenital hearing loss. LVAS may occur as an isolated anomaly or in association with other inner ear malformations. Objective To report three cases of isolated LVAS with a focus on preoperative assessment, surgical issues, and short-term postoperative follow-up with preliminary auditory habilitation outcomes. Resumed Report One girl and two boys with LVAS were assessed and cochlear implantation was performed for each. Various ways of intraoperative management of cerebrospinal fluid gusher and postoperative care and outcomes are reported. Conclusion Cochlear implantation in the deaf children with LVAS is feasible and effective.(AU)


Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Child , Cochlear Implantation , Deafness/diagnosis , Deafness/genetics , Vestibular Aqueduct/physiology , Diagnostic Imaging
10.
Professional Medical Journal-Quarterly [The]. 2015; 22 (2): 149-152
in English | IMEMR | ID: emr-178194

ABSTRACT

This article reviews the most prevalent sensory illness of mammals especially humans - Genetic Deafness or hearing loss [HL]. For genetic hearing loss more than 100 candidate genes have been discovered. The most common candidate gene of these all that is found all around the world is GJB2 gene. Different types of mutations are found in GJB2 gene. Some of these mutations are non-sense while some are sense mutations. This study is focus on mutation in GJB2 gene and its prevalence in different region of the world


Subject(s)
Humans , Deafness/genetics , Genes , Mutation
11.
Rev. méd. Chile ; 141(3): 305-312, mar. 2013. ilus
Article in Spanish | LILACS | ID: lil-677337

ABSTRACT

Maternally Inherited Diabetes and Deafness (MIDD) is caused by mutations in mitochondrial DNA (mtDNA), mainly m.3243A>G. Severity, onset and clinical phenotype of MIDD patients are partially determined by the proportion ofmutant mitochondrial DNA copies in each cell and tissue (heteroplasmy). The identification ofMIDD allows a corred treatment with insulin avoiding drugs that may interfere with mitochondrial electrón chain transpon. We estimated the degree of heteroplasmy ofthe mutation m.3243A>G from blood, saliva, hair root and a muscle biopsy using quantitative PCR (qPCR) in a femóle adult patient. For this purpose, PCR producís were inserted in a vector creatingplasmids with 3243A or G. Mutant and wild-type vectors were mixed in different proportions to créate a calibration curve used to interpólate heteroplasmy percentages with qPCR threshold cycles. The proportions of m.3243A>G heteroplasmy were 62% (muscle), 14% (saliva), 6% (blood leukocytes) and 3% in hair root. Quantitative analysis of heteroplasmy showed marked variations in different tissues (highest in muscle and lowest in blood). Given the relatively high heteroplasmy found in saliva, this type of biológical sample may represent an adequate non-invasive way for assessing the presence of m.3243A>G mutations in epidemiologic studies.


Subject(s)
Female , Humans , Middle Aged , DNA, Mitochondrial/genetics , Deafness/genetics , /genetics , Mutation/genetics , Deafness/diagnosis , Deafness/pathology , /diagnosis , /pathology , Phenotype , Polymerase Chain Reaction/methods
12.
Indian J Hum Genet ; 2013 Jan; 19(1): 54-57
Article in English | IMSEAR | ID: sea-147636

ABSTRACT

BACKGROUND: Mutations of mitochondrial DNA were described into two genes: The mitochondrially encoded 12S RNA (MT-RNR1) and the mitochondrially encoded tRNA serineucn (MT-TS1). The A1555G mutation in MT-RNR1 gene is a frequent cause of deafness in different countries. AIM: The aim of this work was to investigate the frequency of the A1555G mutation in the MT-RNR1 gene in the mitochondrial DNA in Brazilians individuals with nonsyndromic deafness, and listeners. MATERIALS AND METHODS: DNA samples were submitted to polymerase chain reaction and to posterior digestion with the Hae III enzyme. RESULTS: Seventy eight (78) DNA samples of deaf individuals were analyzed; 75 showed normality in the region investigated, two samples (2.5%) showed the T1291C substitution, which is not related to the cause of deafness, and one sample (1.3%) showed the A1555G mutation. Among the 70 non-impaired individuals no A1555G mutation or T1291C substitution was found. CONCLUSION: We can affirm that A1555G mutation is not prevalent, or it must be very rare in normal-hearing subjects in the State of Paraná, the south region of Brazil. The A1555G mutation frequency (1.3%) found in individual with nonsyndromic deafness is similar to those found in other populations, with nonsyndromic deafness. Consequently, it should be examined in deafness diagnosis. The investigation of the A1555G mutation can contribute towards the determination of the nonsyndromic deafness etiology, hence, contributing to the correct genetic counseling process.


Subject(s)
Adolescent , Adult , Aged , Brazil , Child , Child, Preschool , Deafness/epidemiology , Deafness/genetics , DNA, Mitochondrial/genetics , Female , Hearing/genetics , Hearing Loss/genetics , Humans , Male , Middle Aged , Mutation , Young Adult
13.
Arq. bras. endocrinol. metab ; 56(8): 574-577, Nov. 2012. ilus
Article in English | LILACS | ID: lil-660269

ABSTRACT

Maternally-inherited diabetes with deafness (MIDD) is a rare form of monogenic diabetes that results, in most cases, from an A-to-G transition at position 3243 of mitochondrial DNA (m.3243A>G) in the mitochondrial-encoded tRNA leucine (UUA/G) gene. As the name suggests, this condition is characterized by maternally-inherited diabetes and bilateral neurosensory hearing impairment. A characteristic of mitochondrial cytopathies is the progressive multisystemic involvement with the development of more symptoms during the course of the disease. We report here the case of a patient with MIDD who developed hyporeninemic hypoaldosteronism. Arq Bras Endocrinol Metab. 2012;56(8):574-7.


O diabetes mitocondrial (MIDD) é uma forma rara de diabetes monogênico resultante, na maioria dos casos, da mutação mitocondrial A3243G. Essa condição é caracterizada por diabetes de transmissão materna e disacusia neurossensorial. Uma característica das mitocondriopatias é o envolvimento progressivo de outros órgãos ou sistemas, levando ao aparecimento de diversos sintomas durante o curso da doença. Este relato descreve o caso de um paciente com MIDD que, durante o período de acompanhamento, apresentou hipoaldosteronismo hiporreninêmico. Arq Bras Endocrinol Metab. 2012;56(8):574-7.


Subject(s)
Humans , Male , Middle Aged , DNA, Mitochondrial/genetics , Deafness/genetics , /genetics , Hypoaldosteronism/genetics , Point Mutation/genetics , Pedigree
14.
Rev. Soc. Bras. Clín. Méd ; 10(3)maio-jun. 2012.
Article in Portuguese | LILACS | ID: lil-621497

ABSTRACT

JUSTIFICATIVA E OBJETIVOS: A síndrome de Waardenburg é uma doença genética que na forma clássica, os pacientes apresentam várias características físicas marcantes e também surdez neurossensorial. Assim, a partir da exposição dos casos espera-se que os profissionais de saúde tomem conhecimento da doença e possam levantar a hipótese diagnóstica diante de um pacientecom fenótipo sugestivo, tendo em vista que possui baixa frequência na população e seu diagnóstico precoce melhora muito a qualidade de vida dos pacientes.RELATO DOS CASOS: Trata-se de três casos dentro de uma mesma família com características diferentes, inclusive, em relação à surdez genética. Características marcantes estão presentes nos casos, como: dystopia canthorum, epicanto, base nasal proeminente e alargada, maxila encurtada, poliose, encanecimento precoce e surdez congênita neurossensorial. CONCLUSÃO: A grande maioria dos casos desta síndrome é acompanhada de surdez congênita. As características físicas que acompanham a doença permitem o seu diagnóstico clínico, e o ideal seria que esses pacientes fossem diagnosticados ainda na infância para que possam ter acesso precocemente à reabilitação auditiva, contribuindo para melhor desenvolvimento neuropsíquico, levando-se em conta que eles também deverão receber aconselhamento genético.


BACKGROUND AND OBJECTIVES: Waardenburg syndrome is a rare genetic disease that shows variable penetrance and expressivity. In its classic form, patients have several outstanding characteristics, such as deafness. Thus, from the exposure of cases, it is important to be aware of this clinical disease, to health professionals, for early diagnosis, avoiding unnecessary examinations, and achieving effective therapeutic approach.CASE REPORTS: These are three cases in one family with different characteristics, including in relation to genetic deafness. Striking features are present in cases like: dystopia canthorum, epicanthus, prominent and broad nasal base, shortened jaw, poliosis, premature graying and congenital sensorineural deafness. CONCLUSION: Most cases of this syndrome is accompanied by congenital deafness. Therefore, early diagnosis will certainly help in hearing rehabilitation, improving the capacity of developing hearing and communication skills of these individuals.


Subject(s)
Humans , Male , Female , Child , Adult , Early Diagnosis , Deafness/genetics , Waardenburg Syndrome
15.
Indian J Hum Genet ; 2012 May; 18(2): 217-221
Article in English | IMSEAR | ID: sea-143273

ABSTRACT

Families with at least 2 or more individuals having hereditary hearing loss were enrolled from different areas of Khyber Pakhtoonkhwa, mainly from district Peshawar. Detailed history was taken from each family to minimize the presence of other abnormalities and environmental causes for deafness. Families were questioned about skin pigmentation, hair pigmentation, and problems relating to balance, vision, night blindness, thyroid, kidneys, heart, and infectious diseases like meningitis, antibiotic usage, injury, and typhoid. The pedigree structures were based upon interviews with multiple family members, and pedigrees of the enrolled families were drawn using Cyrillic program (version 2.1). All families showed recessive mode of inheritance. I studied 8 families of these 10. For linkage analyses, studies for DFNB1 locus, 3 STR markers (D13S175, D13S292, and D13S787) were genotyped using polyacrylamide gel electrophoresis (PAGE) and haplotypes were constructed to determined, linkage with DFNB1 locus. From a total of 8 families, a single family-10 showed linkage to DFNB1 locus.


Subject(s)
Cohort Studies , Connexins/genetics , Deafness/epidemiology , Deafness/etiology , Deafness/genetics , Genetic Association Studies , Genetic Linkage/genetics , Haplotypes/genetics , Hearing Loss/epidemiology , Hearing Loss/etiology , Hearing Loss/genetics , Humans , Pakistan , Pedigree , Prevalence
16.
Rev. otorrinolaringol. cir. cabeza cuello ; 72(1): 7-14, abr. 2012. ilus
Article in Spanish | LILACS | ID: lil-627555

ABSTRACT

Introducción: Se estima que 1 de cada 1.000 niños presenta hipoacusia severa al nacimiento o en los primeros meses de vida y el 50 por ciento de las hipoacusias congénitas se relacionan con el gen de la conexina 26 (GJB2). En poblaciones caucásicas la variante patogénica 35delG del gen GJB2, que es la más frecuente, se encuentra en 30 por ciento de los pacientes con hipoacusia congénita no sindrómica. En Chile, la frecuencia de esta variante en escolares sordos no está descrita. Objetivos: Estimar la frecuencia de la mutación 35delG del gen GJB2 en niños con sordera congénita no sindrómica y no atribuible a causas ambientales conocidas, de colegios especiales de Santiago. Correlacionar la presencia de 35delG con los antecedentes clínicos de estos niños. Material y método: Se determinó la presencia de la mutación 35delG mediante PCR alelo específico y secuenciación automatizada en 81 escolares. Se buscó asociar la presencia de 35delG y los antecedentes clínicos de los niños mediante la prueba exacta de Fisher. Resultados: En el grupo estudiado, el 11,25 por ciento de los casos presentaron la variante 35delG, siendo ésta más frecuente en los casos en que había antecedentes familiares de sordera. En 8 casos se encontró una variante considerada no patogénica V27I. Conclusión: La frecuencia de la mutación 35delG fue inferior a lo esperado, probablemente debido al método de selección de los niños a estudiar (aquellos cuyos padres no referían causa conocida de sordera, lo cual no fue refrendado por exámenes de laboratorio que permitieran descartar enfermedades infecciosas u otras condiciones causantes de sordera).


Introduction: Congenital hearing loss occurs in 1 in 1000 live births and 50 percent of these cases are related with mutations in the connexin26 gene (GJB2). The 35delG variant is the most common of the known pathogenic alleles in Caucasian populations, reaching a frequency of 30 percent among the non syndromic congenital deaf people. The frequency of this variant has not been described in Chilean deaf children. Aim: To estimate the frequency of the 35delG GJB2 gene mutation in children with non syndromic congenital hearing loss of unknown etiology from deaf schools in Santiago, and to evaluate the association between clinical features of these children and the presence of the 35delG allele. Material and method: The presence of the 35delG mutation was studied by allele specific PCR and automatical sequencing in 81 children. The association between clinical issues and genotypes was explored by Fisher exact test. Results: We found the 35delG variant in 11,25 percent of the children, this mutation was more frequent in familial cases than sporadic cases of deafness. We also found the V27I non pathogenic variant in 8 cases. Conclusion: The frequency of the 35delG mutation was lower than the expected, probably due to the criterion used to select the school children to be studied.


Subject(s)
Humans , Child , Connexins/genetics , Mutation , Students , Deafness/genetics , Chile , DNA , Gene Frequency , Genotype , Polymerase Chain Reaction
17.
Indian J Hum Genet ; 2012 Jan; 18(1): 71-74
Article in English | IMSEAR | ID: sea-139446

ABSTRACT

BACKGROUND: We report on the higher prevalence of deaf-mutes from a village in Jammu and Kashmir State of India. MATERIALS AND METHODS: A cross-sectional study among 79 deaf mutes using pedigree analysis, audiometry, imaging and molecular analysis. RESULTS: A high rate of hereditary deafness with 79 individuals diagnosed to be suffering from non-syndrome deafness in a total population of 2452 individuals residing in the village. INTERPRETATION: Flourishing of intermarriages led to a population with high prevalence of deafness.


Subject(s)
Consanguinity , Deafness/epidemiology , Deafness/etiology , Deafness/genetics , Humans , India , Marriage/trends , Mutism/epidemiology , Mutism/etiology , Mutism/genetics , Rural Population
18.
Journal of Guilan University of Medical Sciences. 2011; 19 (76): 15-21
in Persian | IMEMR | ID: emr-110044

ABSTRACT

Various frequencies of the mtDNA mutations have been reported from different population world wild. Three mitochondrial DNA [mtDNA] mutations including A1555G, A 3243G, and A7445G which occurred in MTRNR1, MTTL1 and MTTS1 genes were considered as the main causes of mitochondrial hearing loss in some populations. To determine the frequency of the A1555G, A3243G, and A7445G mutations in nonsyndromic sensorineural hearing loss subjects in Gilan. Forty six subjects with nonsyndromic sensorineural hearing loss were screened by provided questionnaire and audiogram from Gillan Welfare Organization. PCR-RFLP procedure was used in order to presence the MtDNA of A1555GA 3243G and A7445G mutations and was confirmed by subsequent direct sequencing. There was no MtDNA of A1555G, A3243G and A7445G mutation in the cohort study of 46 deaf individuals. Investigation of PCR-RFLP of the MTTL1 gene for existence A3243G mutation lead to identification a G3316A variant that destroyed other restriction site, in the other site of PCR fragment. Our finding indicated that possibility the association of mitochondrial mutations with deafness is very low in deaf subjects in north of Iran. According to existence the G3316A that its pathogenesis in relation to hearing loss phenotype has not stabilized, the frequency of G3316A is 1.46% that can be had highlights role of mitochondrial mutation in deafness


Subject(s)
Humans , Deafness/genetics , Mitochondria/genetics , Genetic Predisposition to Disease , DNA Mutational Analysis , Mass Screening , Surveys and Questionnaires , Hearing Tests , Polymorphism, Restriction Fragment Length , Polymerase Chain Reaction/methods , Base Sequence , DNA/genetics , Phenotype
19.
Rev. Hosp. Clin. Univ. Chile ; 21(2): 170-176, 2010. tab
Article in Spanish | LILACS | ID: lil-620981

ABSTRACT

Neonatal hearing loss affects 1-3 from every 1000 live newborns. For optimal language and social development, proper diagnosis and treatment must be established before the first 6months of age. In Chile, screening for hearing loss is only performed on high-risk newborns weighting less than 1500 grams. However, about half of the newborns with hearing loss have no risk factors. Given the importance of this disability and the fact that it can be effectively diagnosed, a universal detection program for hearing loss becomes necessary. Further more, effective treatments for hearing loss, like hearing aids and cochlear implants are available in several institutions of our country, including the Clinical Hospital of the University of Chile. Worldwide, the most used screening methods are otoacoustic emissions and auditory brainstem evoked responses, the former, a test that detects the acoustic energy generated by the outer hair cells of the cochlea in response to a brief sound, and the latter a test that measures neural responses of the central auditory pathway. Both are objective and non-invasive techniques. Here we review evidences that support the need of creating a universal newborn hearing screening program in Chile.


Subject(s)
Humans , Male , Female , Infant, Newborn , Infant , Infant, Newborn , Hearing Loss/congenital , Hearing Loss/epidemiology , Hearing Loss/genetics , Deafness/congenital , Deafness/diagnosis , Deafness/epidemiology , Deafness/genetics
20.
Article in English | IMSEAR | ID: sea-135907

ABSTRACT

Non syndromic hearing impairment is a common sensory disorder, which affects one in 600 newborns. Though more than 50 nuclear genes are involved in causing non syndromic hearing impairment, mutations in the connexin 26 (GJB2) gene explain a high proportion of congenital deafness in several populations worldwide. The diversity of genes and genetic loci implicated in hearing loss defines the complexity of the genetic basis of hearing. This review focuses on the role of connexin 26 and mitochondrial 12S rRNA genes in hearing which will be helpful for better understanding of genes in sporadic and aminoglycosideinduced non syndromic hearing impairment.


Subject(s)
Aminoglycosides/adverse effects , Connexins/genetics , Connexins/metabolism , Deafness/chemically induced , Deafness/genetics , Hearing/physiology , Hearing Loss/chemically induced , Hearing Loss/genetics , Humans , Mitochondria/genetics , Mutation , RNA, Ribosomal/genetics , RNA, Ribosomal/metabolism
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