Background The mutation frequencies of three common deafness genes （MT-RNR1 m.1555A〉G,GJB2,and SLC26A4） among patients with nonsyndromic sensorineural hearing loss （NSHL） were different in previous studies.Incons...Background The mutation frequencies of three common deafness genes （MT-RNR1 m.1555A〉G,GJB2,and SLC26A4） among patients with nonsyndromic sensorineural hearing loss （NSHL） were different in previous studies.Inconsistent selection criteria for recruiting patients could have led to differences in estimating the frequencies of genetic mutations thus resulting in different mutation frequencies among these studies.The aim of this study was to reveal the differences in the mutation spectrums of the three common genes between familial and sporadic Chinese Han patients.Methods Totally,301 familial probands and 703 sporadic patients with NSHL were enrolled in this study.Three genes,MT-RNR1 m.1555A〉G,GJB2,and SLC26A4,were screened for mutation in our study cohort.A X2 test was performed to compare the mutation frequencies between the two groups.Results The study showed that the disease-causing mutation frequencies of MT-RNR1 m.1555A〉G,GJB2,and SLC26A4 were 12.29%,14.62%,and 18.27% in familial probands and 3.56%,18.63%,and 18.92% in sporadic patients,respectively.The mutation frequency of MT-RNR1 m.1555A〉G in familial probands was significantly higher than in sporadic patients （X2 test,P=0.000）,while there were no significant differences in the mutation frequencies of GJB2 and SLC26A4 between the familial and sporadic groups （X2 test,P 〉0.05）.Conclusions It is necessary to reveal the differences in gene mutation frequencies between patients of different sources or characteristics by comparative studies in order to avoid selection bias.The mutations of GJB2,SLC26A4,and MTRNR1 m.1555A〉G are the most important etiological factors in Chinese Han patients,among which SLC26A4 might be the most frequent.展开更多
Bicarbonate is one of the major anions in mammalian tissues and extracellular fluids. Along with accompanying H+, HCO3- is generated from CO2 and H2 O, either spontaneously or via the catalytic activity of carbonic an...Bicarbonate is one of the major anions in mammalian tissues and extracellular fluids. Along with accompanying H+, HCO3- is generated from CO2 and H2 O, either spontaneously or via the catalytic activity of carbonic anhydrase. It serves as a component of the major buffer system, thereby playing a critical role in pH homeostasis. Bicarbonate can also be utilized by a variety of ion transporters, often working in coupled systems, to transport other ions and organic substrates across cell membranes. The functions of HCO3- and HCO3--transporters in epithelial tissues have been studied extensively, but their functions in heart are less well understood. Here we review studies of the identities and physiological functions of Cl-/HCO3- exchangers and Na+/HCO3-cotransporters of the SLC4 A and SLC26 A families in heart. We also present RNA Seq analysis of their cardiac mRNA expression levels. These studies indicate that slc4a3(AE3) is the major Cl-/HCO3- exchanger and plays a protective role in heart failure, and that Slc4a4(NBCe1) is the major Na+/HCO3- cotransporter and affects action potential duration. In addition, previous studies show that HCO3- has a positive inotropic effect in the perfused heart that is largely independent of effects on intracellular Ca2+. The importance of HCO3- in the regulation of contractility is supported by experiments showing that isolated cardiomyocytes exhibit sharply enhanced contractility, with no change in Ca2+ transients, when switched from Hepes-buffered to HCO3-- buffered solutions. These studies demonstrate that HCO3- and HCO3--handling proteins play important roles in the regulation of cardiac function.展开更多
Enlarged vestibular aqueduct(EVA)is a radiologic malformation of the inner ear most commonly seen in children with sensorineural hearing loss.Most cases of EVA with hearing loss are caused by biallelic mutations of SL...Enlarged vestibular aqueduct(EVA)is a radiologic malformation of the inner ear most commonly seen in children with sensorineural hearing loss.Most cases of EVA with hearing loss are caused by biallelic mutations of SLC26A4.In this review,we discuss the potential mechanisms underlying the pathogenesis of hearing loss with EVA due to malfunction of SLC26A4,the detection rates of SLC26A4 mutations in EVA patients from different populations,and the role of other genetic factors(eg,mutations in FOXI1 and KCNJ10)as etiologic contributors to EVA.Elucidating the molecular etiology of EVA-associated hearing loss may facilitate genetic counseling and lead to potential therapeutic strategies.展开更多
基金This work was supported by grants from the National Key Basic Research Program of China （No. 2014CB943001）, the National Natural Science Foundation of China, Major Project （No. 81120108009）, the Key Medical Technology Research Program of China People＇s Liberation Army （No. BWS11J026）, and the Nursery Fotmdation of China People＇s Liberation Army （No. 14KMZ04）.
文摘Background The mutation frequencies of three common deafness genes （MT-RNR1 m.1555A〉G,GJB2,and SLC26A4） among patients with nonsyndromic sensorineural hearing loss （NSHL） were different in previous studies.Inconsistent selection criteria for recruiting patients could have led to differences in estimating the frequencies of genetic mutations thus resulting in different mutation frequencies among these studies.The aim of this study was to reveal the differences in the mutation spectrums of the three common genes between familial and sporadic Chinese Han patients.Methods Totally,301 familial probands and 703 sporadic patients with NSHL were enrolled in this study.Three genes,MT-RNR1 m.1555A〉G,GJB2,and SLC26A4,were screened for mutation in our study cohort.A X2 test was performed to compare the mutation frequencies between the two groups.Results The study showed that the disease-causing mutation frequencies of MT-RNR1 m.1555A〉G,GJB2,and SLC26A4 were 12.29%,14.62%,and 18.27% in familial probands and 3.56%,18.63%,and 18.92% in sporadic patients,respectively.The mutation frequency of MT-RNR1 m.1555A〉G in familial probands was significantly higher than in sporadic patients （X2 test,P=0.000）,while there were no significant differences in the mutation frequencies of GJB2 and SLC26A4 between the familial and sporadic groups （X2 test,P 〉0.05）.Conclusions It is necessary to reveal the differences in gene mutation frequencies between patients of different sources or characteristics by comparative studies in order to avoid selection bias.The mutations of GJB2,SLC26A4,and MTRNR1 m.1555A〉G are the most important etiological factors in Chinese Han patients,among which SLC26A4 might be the most frequent.
基金Supported by National Institutes of Health Grants HL061974 to Shull GEand ES017263 to Wang HS
文摘Bicarbonate is one of the major anions in mammalian tissues and extracellular fluids. Along with accompanying H+, HCO3- is generated from CO2 and H2 O, either spontaneously or via the catalytic activity of carbonic anhydrase. It serves as a component of the major buffer system, thereby playing a critical role in pH homeostasis. Bicarbonate can also be utilized by a variety of ion transporters, often working in coupled systems, to transport other ions and organic substrates across cell membranes. The functions of HCO3- and HCO3--transporters in epithelial tissues have been studied extensively, but their functions in heart are less well understood. Here we review studies of the identities and physiological functions of Cl-/HCO3- exchangers and Na+/HCO3-cotransporters of the SLC4 A and SLC26 A families in heart. We also present RNA Seq analysis of their cardiac mRNA expression levels. These studies indicate that slc4a3(AE3) is the major Cl-/HCO3- exchanger and plays a protective role in heart failure, and that Slc4a4(NBCe1) is the major Na+/HCO3- cotransporter and affects action potential duration. In addition, previous studies show that HCO3- has a positive inotropic effect in the perfused heart that is largely independent of effects on intracellular Ca2+. The importance of HCO3- in the regulation of contractility is supported by experiments showing that isolated cardiomyocytes exhibit sharply enhanced contractility, with no change in Ca2+ transients, when switched from Hepes-buffered to HCO3-- buffered solutions. These studies demonstrate that HCO3- and HCO3--handling proteins play important roles in the regulation of cardiac function.
文摘Enlarged vestibular aqueduct(EVA)is a radiologic malformation of the inner ear most commonly seen in children with sensorineural hearing loss.Most cases of EVA with hearing loss are caused by biallelic mutations of SLC26A4.In this review,we discuss the potential mechanisms underlying the pathogenesis of hearing loss with EVA due to malfunction of SLC26A4,the detection rates of SLC26A4 mutations in EVA patients from different populations,and the role of other genetic factors(eg,mutations in FOXI1 and KCNJ10)as etiologic contributors to EVA.Elucidating the molecular etiology of EVA-associated hearing loss may facilitate genetic counseling and lead to potential therapeutic strategies.
