Temporal Bone Histopathologic and Genetic Studies in Mohr-Tranebj??rg Syndrome (DFN-1)

Abstract

Sensorineural hearing loss in Mohr-Tranebjaerg syndrome is the result of a postnatal, progressive, severe auditory neuropathy.

Benefits and costs of universal hearing screening programme

“…Anatomical studies have shown that the hearing loss is consecutive to inner hair cells [12,13] or auditory nerve [14,15] anomalies. It is known now that several factors may increase the risk of auditory neuropathy such as prematurity, anoxia, hyperbilirubinemia [16], and several genetic diseases [17][18][19][20][21]. For this reason, we reintroduced the notion of high-risk newborns, in which the auditory screening tests include the recording of aABR.…”

The genetic basis of auditory neuropathy spectrum disorder (ANSD)

“…MTS is characterised by severe deafness, dystonia and sometimes are accompanied by cortical deterioration of vision and mental deterioration. MTS is reported to be associated with ANSD, and presented with X-linked inheritance with mutation in TIMM8A gene, which is also known as deafness dystonia peptide (DDP) genes [9,37,71]. The temporal bone investigations have showed near complete loss of cochlear neuronal cells and spiral ganglion cells, and severe loss of vestibular neurons in such cases.…”

“…By contrast, congenital ANSD is mainly caused by genetic abnormality, which may be either isolated or associated with other syndromes. For example, Charcot-Marie-Tooth (CMT) disease [9,[22][23][24][25][26][27][28][29], Leber's Hereditary Optic Neuropathy (LHON) [30], Autosomal Dominant Optic Atrophy (ADOA) [31][32][33], Autosomal Recessive Optic Atrophy (OROA) [34], Fredreich's Ataxia [35,36], Mohr-Tranebjaerg Syndrome (MTS) [9,37,38], Refsum's Disease [38,39], Mitochondrial Disease [30,[40][41][42]. However, there might also be occurrences of ANSD with mitochondrial inheritance with associated anomalies, which are outside the boundaries of any existing syndromes.…”

Cochlear implantation in deafness-dystonia-optic neuronopathy (DDON) syndrome

“…The encoded protein is 97 amino acids and functions as a translocase in the import of metabolite transporters from the cytoplasm into the mitochondrial inner membrane, classifying DDON syndrome a type of mitochondrial disease. Temporal bone histopathology shows degeneration of spiral ganglion cells with preservation of the Organ of Corti, which calls into question the benefit of cochlear implantation (CI) in this patient population [8,9] .To our knowledge, this report is the first to describe the outcome of cochlear implantation in a patient with DDON syndrome.…”