A novel mutation in the translocase of inner mitochondrial membrane 8 homolog A gene in a family with Mohr-Tranebjaerg syndrome

Abstract

Objective To report the clinical and genetic features in a family with Mohr-Tranebjaerg syndrome (MTS). Methods After collecting clinical data of the family, visual and auditory evoked potentials, pure tone audiometry, transient evoked otoacoustic emissions and distortion product otoacoustic emissions were carried out in proband (Ⅲ5).The translocase of inner mitochondrial membrane 8 homolog A (TIMM8A) gene was sequenced in proband, Ⅰ2, Ⅱ4 and Ⅱ6. Results Ⅲ5, a 15-year-old boy presented with deafness, slurred speech, difficulty in finger extension and dystonia gradually since 2 years old. Ⅲ1, Ⅲ2and Ⅲ3presented with deafness at the age of 2.Ⅰ2, Ⅱ2, Ⅱ4and Ⅱ6showed mild decreased visual acuity at the age of 12.Visual evoked potentials revealed prolonged P100 latency in both eyes.Pure tone audiometry revealed severe sensorineural hearing loss.The auditory evoked potentials showed no wave in the bilateral ears.Otoacoustic emissions were not elicited bilaterally.A novel c.133-2del A mutation in TIMM8A gene was identified in Ⅲ5, Ⅰ2, Ⅱ4and Ⅱ6. Conclusions We confirm the MTS caused by a novel c.133-2del A mutation in TIMM8A gene.Except for the deafness, the development of other symptoms of the disease vary obviously from case to case in the same family.The female carriers with mild lesion of optic nerves. Key words: Dystonia; Intellectual disability; Optic atrophy; Deaf-blind disorders; Membrane transport proteins; Mutation