Mutational analysis of candidate genes in a Chinese pedigree with dominantly inherited auditory neuropathy / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#Three genes including the OTOF, the DFNB59 and the DIAPH3 have been implicated previously in human non-syndromic auditory neuropathy. In this study, we aim to investigate whether DIAPH3 gene or the known deafness loci of 25 cloned autosomal dominant deafness (DFNA) genes contribute to the nonsyndromic hearing loss of a Chinese pedigree with dominantly inherited auditory neuropathy (AN).@*METHOD@#Nine members of the kernal pedigree in this family were selected. Genomic DNA was isolated from the peripheral leukocytes of the subjects using the Puregene DNA Isolation Kits. Firstly, the 5'UTR of DIAPH3 gene was PCR amplified in all subjects. Then, the DNA fragments spanning the entire coding regions of DIAPH3, GJB2 and GJB3 genes, and 50 exons in other 23 cloned DFNA genes were amplified using specific primers. Each fragment was purified and analyzed by direct sequencing. The resultant sequence data were compared with the standard sequence to identify deafness-associated mutations.@*RESULT@#PCR amplifications were successfully conducted. We failed to detect the presence either of c. --172G > A mutation in the 5'UTR that have been reported, or any other deafness-associated mutations in the whole DIAPH3 gene, by sequence analysis. We also did not find any known deafness-causing mutations among the 25 cloned DFNA genes.@*CONCLUSION@#The DIAPH3 gene, and the known deafness loci of 25 cloned DFNA genes seem not contribute to the pathogenesis of this Chinese AN family in this study, which suggesting new gene(s) involvement.

Mutation analysis of mitochondrial 12S rRNA gene G709A in a maternally inherited pedigree with non-syndromic deafness / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the relationship of mitochondrial DNA mutations with inherited deafness in a maternally inherited pedigree with non-syndromic deafness.</p><p><b>METHODS</b>The diagnosis was validated by hearing tests. Blood samples were collected from 18 maternal members of the family and 53 controls including 6 paternal members, 7 spouses and 40 unrelated individuals. DNA was extracted from the leukocytes in blood samples. The gene fragments of mitochondrial DNA 12S rRNA, tRNA(Ser(UCN)) and GJB2 gene were amplified by polymerase chain reaction(PCR). PCR products were analyzed by sequencing. Computerized 12S rRNA secondary structure modeling was carried out to characterize the mutation found in the family.</p><p><b>RESULTS</b>A novel mitochondrial DNA 12S rRNA 709 G to A transition was detected from all maternal members including 8 patients with hearing loss and other 10 symptom-free maternal members. Non-maternal members and other controls did not carry this mutation. In addition, the tRNA(Ser(UCN))A7445G, 12S rRNA A1555G and GJB2 gene mutations were not observed in the study. Computerized modeling showed that this mutation changed the eighth and ninth loop-stem structure of the 12S rRNA secondary structure.</p><p><b>CONCLUSION</b>In this family, 8 deaf patients carried the mitochondrial DNA 12S rRNA 709 G to A mutation, which is highly conservative in healthy adults. It was confirmed that the mitochondrial DNA 12S rRNA gene G709A was associated with non-syndromic inherited hearing loss. The other 10 maternal members carried the mutation, but they did not suffer from deafness, which might suggest that the G709A mutation may cause hearing impairment in combination with a synergistic effect of some other nuclear modifier genes.</p>

Sequence analysis of DFNB59 gene in a Chinese family with dominantly inherited auditory neuropathy / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate if the DFNB59 gene contributes to the hearing loss of a Chinese pedigree with dominantly inherited auditory neuropathy (AN).@*METHOD@#Nine members in four generations of the family were selected for this study. Genomic DNA was isolated from the peripheral leukocytes of the patients using the pure gene DNA isolation kits. Firstly, the subjects DNA fragment was PCR amplified using specific primers corresponding to exon 2 and 4 of the DFNB59 gene. Each fragment was purified and subsequently analyzed by direct sequencing in an applied biosystems 3730 automated DNA sequencer. The whole coding sequence of DFNB59 gene of one family patient were then PCR amplified and submitted for sequence analysis as described above. The resultant sequence data were compared with the standard sequence to identify deafness-associated mutations.@*RESULT@#PCR amplifications were successfully conducted in all the subjects. We failed to detect the presence either of mutations T54I and R183W in the exon 2 and exon 4 that have been reported, or any other deafness-associated mutations in the whole DFNB59 gene, by sequence analysis.@*CONCLUSION@#The DFNB59 gene seems not contribute to the pathogenesis of this Chinese AN family, which suggesting new gene(s) involvement.

Sequence analysis of OTOF gene in a Chinese pedigree with autosomal dominant auditory neuropathy / 临床耳鼻咽喉头颈外科杂志

OBJECTIVE@#To investigate if the OTOF gene contributes to the non-syndromic hearing loss of a Chinese pedigree with dominantly inherited auditory neuropathy (AN).@*METHOD@#The subjects included were 9 live individuals in an autosomal dominant AN pedigree, 3 sporadic AN patients and 3 normal-hearing controls. Genomic DNA was isolated from the peripheral leukocytes of the subjects using the Pure gene DNA Isolation Kits. Firstly, the whole coding sequence of OTOF gene of one family patient were PCR amplified using specific primers. Each fragment was purified and subsequently analyzed by direct sequencing in an Applied Biosystems 3 730 automated DNA sequencer. The resultant sequence data were compared with the standard sequence to identify deafness-associated mutations. Other DNA samples were then screened for these mutations by PCR amplification and sequence analysis.@*RESULT@#PCR amplifications were successfully conducted in all the subjects. Comparison of the resultant OTOF sequence in one family patient with the standard sequence identified 10 nucleotide variants which do not lead to amino acid change. These mutations were also detectable in other family individuals, 3 sporadic AN patients and 3 normal-hearing controls.@*CONCLUSION@#The OTOF does not seem to contribute to the pathogenesis of this Chinese AN family, which suggest new gene(s) involvement.