Hereditary cochleovestibular dysfunction due to a COCH gene mutation (DFNA9): a follow‐up study of a family

Hereditary cochleovestibular dysfunction due to a COCH gene mutation (DFNA9): a follow‐up study of a family Cochleovestibular impairment was evaluated, in relation to age, in a longitudinal follow‐up study on a Dutch family with a DFNA9 trait caused by a Pro51Ser mutation in the COCH gene on chromosome 14q12‐q13. Fourteen cases were genotyped. The onset age of progressive impairment reported by the mutation carriers was between age 35 and 45 years. Pure‐tone thresholds deteriorated by about 2–7 dB per year (mean 3.8 dB per year) in a variable, often asymmetrical, fashion. One mutation carrier developed recurrent episodes of vertigo accompanied by nausea and vomiting, resembling Ménière's disease. Two others developed special susceptibility for motion sickness and appeared to have a hyperactive vestibulo‐ocular reflex. More advanced stages of vestibular impairment, i.e. vestibular hyporeflexia and complete vestibular areflexia, were eventually found in a number of cases. DFNA9/COCH should be considered as a possible cause in patients developing combined progressive cochlear and vestibular impairment, or suspected hereditary Ménière‐like disease, from around middle age.     

COCH基因与miR-96的相关性研究

目的研究COCH基因与小分子RNAmiR-96的相互作用,探讨miR-96的表达变化是否对COCH基因有影响。方法在细胞水平上,转染miR-96的miRNA模拟物和miRNA抑制物而改变miR-96的表达水平,通过荧光定量PCR检测COCH基因的表达变化情况。结果 miR-96的表达变化与COCH基因的表达变化呈正相关关系。结论结果显示miR-96并没有对COCH基因进行负调控,而是呈现协同作用,甚至miR-96有可能作用于其他相关因子而导致COCH基因表达上调,从而影响COCH基因在耳蜗及前庭功能变化中的作用。     

Identification of Pathogenic Mechanisms of COCH Mutations,Abolished Cochlin Secretion,and Intracellular Aggregate Formation: Genotype–Phenotype Correlations in DFNA9 Deafness and Vestibular Disorder

Mutations in COCH (co agulation factor C h omology) cause autosomal‐dominant nonsyndromic hearing loss with variable degrees of clinical onset and vestibular malfunction. We selected eight uncharacterized mutations and performed immunocytochemical and Western blot analyses to track cochlin through the secretory pathway. We then performed a comprehensive analysis of clinical information from DFNA9 patients with all 21 known COCH mutations in conjunction with cellular and molecular findings to identify genotype–phenotype correlations. Our studies revealed that five mutants were not secreted into the media: two von Willebrand factor A (vWFA) domain mutants, which were not transported from the endoplasmic reticulum to Golgi complex and formed high‐molecular‐weight aggregates in cell lysates, and three LCCL domain mutants, which were detected as intracellular dimeric cochlins. Mutant cochlins that were not secreted and accumulated in cells result in earlier age of onset of hearing defects. In addition, individuals with LCCL domain mutations show accompanying vestibular dysfunction, whereas those with vWFA domain mutations exhibit predominantly hearing loss. This is the first report showing failure of mutant cochlin transport through the secretory pathway, abolishment of cochlin secretion, and formation and retention of dimers and large multimeric intracellular aggregates, and high correlation with earlier onset and progression of hearing loss in individuals with these DFNA9‐causing mutations.     

一个遗传性耳聋伴前庭功能障碍家系的分子病因学研究

目的:对1个遗传性耳聋伴前庭功能障碍家系进行遗传方式?表型特征及致病基因的分析,以研究其分子病因?方法:对门诊1例遗传性聋伴眩晕患者进行家系调查?病史收集及相应的听力学和前庭功能检查?利用目标基因捕获和大规模平行测序技术,对家系先证者进行可能致病突变筛查,包括靶向104种与遗传性听力损失相关的基因和3个microRNA分子?进一步对获得的候选突变基因进行编码区序列验证分析?结果:目标基因捕获测序结果发现先证者COCH基因第11外显子上存在c.1458C>G(p.T352S)的杂合突变?进一步对家系中所有患者和有血缘关系的正常个体进行了遗传共分离分析,发现该杂合突变在该家系中仅有Ⅰ2?Ⅱ1?Ⅱ5?Ⅱ9?Ⅱ13和Ⅳ1存在相同的杂合突变,而Ⅱ11和Ⅲ1表现为该突变的纯合子,表明该杂合突变不存在共分离现象,因此可以排除其为该家系致病突变的可能性?对先证者Ⅲ14 COCH基因全部12个外显子的序列测定结果未发现其他突变?结论:此家系为常染色体显性遗传性非综合征型耳聋伴前庭功能障碍,但初步筛查结果未发现已知耳聋相关基因,包括COCH基因的可疑致病突变?因此,该家系的分子病因可能存在一新基因的突变?     

一个中国DFNA9家系的听力学及前庭功能特点

目的 分析携带COCH基因新突变的一个中国DFNA9家系成员的听力学及前庭功能特点.方法 对家系成员进行详尽的听力学及前庭功能检查,包括纯音测听、听性脑干反应、耳蜗电图;视眼动、冷热试验、旋转试验、前庭诱发性肌源性电位,评价有无听力及前庭损害.结果 该家系患者听力学检查表现为以高频下降为主的进行性感音神经性聋;前庭功能检查正常.结论 中国DFNA9家系的所有vWFA2结构域突变携带者一生中均无前庭障碍的症状,详尽的前庭功能检查正常.中国DFNA9家系的临床资料分析表明DFNA9存在基因型和表现型的相关性.     

Whole exome sequencing identifies a novel DFNA9 mutation,C162Y

We report the genetic analysis of a Chinese family with autosomal dominant non‐syndromic progressive sensorineural hearing loss. Taking advantage of next‐generation high‐throughput DNA sequencing technology, we combined whole exome capture sequencing with Sanger direct sequencing. A novel missense mutation in the coagulation factor C homolog (COCH) gene was identified in a consanguineous Chinese family. This missense mutation in the seventh exon (c.889G>A; p.C162Y) of COCH is most probably a disease‐causing mutation and it segregates with the disease. The mutation is not found in the single nucleotide polymorphism (SNP) database, the yhSNP database, the 1000 genomes SNP database or in matching normal controls. It is the first reported autosomal dominant nonsyndromic sensorineural deafness 9 (DFNA9) mutation outside the limulus factor C, cochlin and late gestation lung protein and von Willebrand factor 2 domain, i.e. the first reported DFNA9 mutation in the intervening domain of cochlin, encoded by the COCH gene. In the future, we will focus on functional studies of this mutation.     

COCH基因与miR-96的相关性研究

目的研究COCH基因与小分子RNAmiR-96的相互作用,探讨miR-96的表达变化是否对COCH基因有影响。方法在细胞水平上,转染miR-96的miRNA模拟物和miRNA抑制物而改变miR-96的表达水平,通过荧光定量PCR检测COCH基因的表达变化情况。结果 miR-96的表达变化与COCH基因的表达变化呈正相关关系。结论结果显示miR-96并没有对COCH基因进行负调控,而是呈现协同作用,甚至miR-96有可能作用于其他相关因子而导致COCH基因表达上调,从而影响COCH基因在耳蜗及前庭功能变化中的作用。     

Extralabyrinthine Manifestations of DFNA9

DFNA9 is an autosomal dominant cause of non-syndromic adult-onset sensorineural hearing loss with associated variable vestibular dysfunction caused by mutations in the COCH gene. DFNA9 has previously been characterized by the presence of unique histopathologic features limited to the cochlear and vestibular labyrinth. This report describes newly discovered extralabyrinthine findings within the middle ear in DFNA9 and discusses their implications. The histopathologic anatomy of extralabyrinthine structures was reviewed in 12 temporal bones from seven individuals with DFNA9 and compared with age-matched controls. All temporal bones with DFNA9 had abnormal deposits within the tympanic membrane, incudomalleal joint, and incudostapedial joint. Hematoxylin and eosin stain and Movat’s pentachrome stain both revealed different staining patterns of the extralabyrinthine deposits compared with the intralabyrinthine deposits suggesting that the composition of the deposits varies with location. The deposits within the tympanic membrane resembled cartilage morphologically and stained positively for aggrecan, an extracellular matrix protein found in cartilage. However, the cellular component of the tympanic membrane deposits did not stain with immunomarkers for chondrocytes (s100 and connective tissue growth factor). These novel findings in DFNA9 have implications for the phenotypic expression of the disorder and the clinical workup of adult-onset sensorineural hearing loss.