RESUMO
Eighteen different sequence changes, including three novel alterations, were detected in GJB2, encoding connexin 26, in 371 Turkish probands with non-syndromic sensorineural hearing loss. Two frequently detected mutations, 35delG and delE120, were shown to have single origins based on the conserved genotypes of two closely linked microsatellite and five single nucleotide polymorphism markers. Carrier frequencies of 35delG and delE120 in Egypt and Turkic populations of the Near East provide insights about the origin of these two mutations.
Assuntos
Conexinas/genética , Mutação da Fase de Leitura , Perda Auditiva Neurossensorial/genética , Adolescente , Adulto , Sequência de Bases , Criança , Pré-Escolar , Conexina 26 , Saúde da Família , Feminino , Frequência do Gene , Marcadores Genéticos , Genótipo , Humanos , Masculino , Dados de Sequência Molecular , Mutação , Linhagem , Topografia Médica , TurquiaAssuntos
Proteínas de Transporte/genética , Testes Genéticos , Perda Auditiva Neurossensorial/genética , Hipotireoidismo/genética , Proteínas de Membrana Transportadoras , Mutação/genética , Sequência de Bases , Conexina 26 , Conexinas/genética , Orelha Interna/diagnóstico por imagem , Eletroforese em Gel de Poliacrilamida , Feminino , Perda Auditiva Neurossensorial/complicações , Humanos , Hipotireoidismo/complicações , Masculino , Repetições de Microssatélites/genética , Linhagem , Análise de Sequência de DNA , Transportadores de Sulfato , Síndrome , Tomografia Computadorizada por Raios X , TurquiaRESUMO
UNLABELLED: Considerable differences on the frequencies of the mitochondrial 12S rRNA A1555G and tRNA(Ser(UCN)) A7445G mutations have been reported in different populations. Our screening of 168 patients coming from independent Turkish families with prelingual sensorineural non-syndromic deafness revealed three deaf children with A1555G (1.8%) but no examples of A7445G. One proband with the mitochondrial A1555G mutation has also evidence for right parietal infarct on a brain imaging study, for which common thrombotic mutations were found to be negative. CONCLUSION: This study shows that the mitochondrial A1555G mutation is among the significant causes of prelingual non-syndromic deafness in the Turkish population.
Assuntos
Antibacterianos/efeitos adversos , DNA Mitocondrial/genética , Surdez/induzido quimicamente , Surdez/genética , Mutação , Adolescente , Aminoglicosídeos , Infarto Cerebral/complicações , Criança , Pré-Escolar , DNA Mitocondrial/efeitos dos fármacos , Surdez/epidemiologia , Surdez/etiologia , Feminino , Humanos , Masculino , Prevalência , Turquia/epidemiologiaRESUMO
Mutations in the GJB2 (connexin 26-Cx26) gene are responsible for 20-50% of cases with prelingual non-syndromic deafness in a large part of the world including Turkey. Although most of the cases with Cx26 deafness have a recessive mode of inheritance, a small group of families demonstrated dominant or pseudodominant inheritance. In this report we present a Turkish family in which the proband had congenital profound deafness and was found to be homozygous for the 35delG mutation, whereas the father and a paternal uncle who had milder, late-onset sensorineural hearing loss had compound heterozygous 35delG and L90P mutations. This family and previous reports with the L90P mutation demonstrate that the hearing loss associated with the L90P/35delG genotype is consistently milder than that of 35delG homozygotes. GJB2 gene screening should be considered in families with seemingly dominant inheritance and late-onset moderate hearing loss.
