An analysis on hereditary deafness gene test results of 93 cases of deaf children / 预防医学

Objective To learn the situation of deafness gene among deaf children and to provide suggestions for intervention.Methods Twenty hot spot mutations of the common deafness genes of GJB2,GJB3,MT -RNR1,SLC26A4 for 93 deafness patients were detected by MALDI -TOF -MS,and Sanger sequencing method was used to detect the whole exon of the gene for the heterozygous mutant.Results A total of 48 cases were detected with mutation among the 93 patients using MALDI -TOF -MS,and the detection rate was 51.61%.Thirty five cases were GJB2 mutation,and the detection rate was 37.63%,in which 24 cases were homozygous mutation or compound heterozygous mutations and 11 cases were heterozygous mutation.Thirteen cases were SLC26A4 mutation,and the detection rate was 13.98%,in which 6 cases were homozygous mutation or compound heterozygous mutations and 7 cases were single heterozygous mutation.Mutation in MT -RNR1 and GJB3 gene were not detected.Among the 18 mutation cases,17 cases were detected the whole exon of the gene with mutation using Sanger sequencing,and 12 cases were detected other loci heterozygous mutation (70.59%).And a total of 42 cases were found out the cause of the deafness,and the detection rate was 45.16%.Conclusion The mutation of the common deafness gene in patients with deafness in the region has a high detection rate.The whole exon of the gene with mutation was detected,which can improve the detection rate of the cause of deafness.

Prevalence of the 35delG mutation in the GJB2 gene in two samples of non-syndromic deaf subjects from Chile

Hearing loss is the most common inherited sensorial deficiency in humans; about 1 in 1000 children suffer from severe or profound hearing loss at birth. Mutations in the GJB2 gene are the most common cause of prelingual, non-syndromic autosomal recessive deafness in many populations; the c.35delG mutation is the most common in Caucasian populations. The frequency of the c.35delG mutation was estimated in two samples of deaf patients from Santiago, Chile. Unrelated non-syndromic sensorioneural deaf patients were examined: Group 1 consisted of 47 unrelated individuals with neurosensory deafness referred to the Chilean Cochlear Implant Program; Group 2 included 66 school children with prelingual deafness attending special education institutions for deaf people. Individuals with profound to moderate isolated neurosensory hearing loss with unknown etiology were included. The presence of the c.35delG mutation was evaluated by the allele-specific polymerase chain reaction method (PCR), and in some cases it was confirmed by direct DNA sequencing of the coding region of the GJB2 gene. Deaf relatives were present in 20.3% of the cases. We found 19.5% (22/113) patients with the c.35delG mutation, 6 of them homozygous; these rates are similar to frequencies found in other Latin American countries.

Frecuencia de la mutación 35delG del gen GJB2 (conexina 26) en una muestra de escolares sordos de Santiago / Frequency of the 35delG mutation of GJB2 (connexin 26) in a sample of deafschool children in Santiago

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.

Novel multiplex primer extension and denaturing high-performance liquid chromatography for genotyping of the deafness gene mutations / 中南大学学报(医学版)

To find a rapid and accurate genotyping method for specific non-syndromic hearing loss (NSHL)-causing gene mutations for disease diagnosis in different ethnic populations.Methods We performed a novel multiplex primer extension (PE) reaction in combination with denaturing high-performance liquid chromatography (DHPLC) to simultaneously detect and genotype the 6 most common mutations in 180 patients with NSHL (GJB2-235delC,GJB2-299delAT,PDS-A2168G,PDS IVS7-2A ＞ G,mtDNA-A1555G,and mtDNA-C1494T) in Chinese population.This method involved the amplification of the target sequence,followed by a purification step,a multiplex PE reaction,and DHPLC analysis performed on the Transgenomic Wave DNA fragment analysis system under fully-denaturing conditions.Results In a blind analysis,this technique successfully and accurately genotyped 100％ of the samples simultaneously characterized by direct sequencing.Conclusion Combination of PE and DHPLC is simple,rapid,accurate,and cost-effective for genotyping common disease-causing mutations,including substitutions,insertions,and deletions in NSHL,and may be successfully used in other genetic diseases.

Expression of Human Connexin26 in COS-7 Cells / 热带医学杂志

Objective To construct the eukaryotic expression plasmid for the expression of human Connexin26 in COS-7 cells.Methods Total RNA was isolated from human peripheral blood lymphocytes and used as template for the PCR cloning of the human Connexin26 gene.The human Cx26 cDNA containing the 678 bp whole coding region of the human Connexin26 gene was amplified by PCR using specific primers and cloned into the pCI-neo vector to construct the recombinant eukaryotic expression plasmid,pCI-Cx26.The recombinant plasmid was identified by restriction endonuclease digestion,and transfected into COS-7 cells by liposome.The expression of Cx26 mRNA and the protein were analyzed by RT-PCR and SDS-PAGE,respectively.Results Restriction endonuclease digestion analysis verified successful construction of the recombinant plasmid,pCI-Cx26.The expression of Cx26 mRNA and protein in the transfected COS-7 cells were detected by RT-PCR and SDS-PAGE,respectively.Conclusion The eukaryotic expression plasmid for human Cx26 has been constructed successfully with the capability of expression in COS-7 cells.