The proband, a 57-year-old man, was referred to our tertiary referral hospital for progressive hearing loss, which coexisted with optic neuropathy. The question was raised whether he was a good candidate for cochlear implantation. Medical history showed that both his mother and brother also had optic neuropathy and hearing loss. shows the pedigree of this family. Informed consent was obtained from both the proband and his family to participate in this study. The research adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board (Commissie Mensgebonden Onderzoek), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Figure 1 The p.Lys836Asn mutation in the studied family with autosomal dominant optic neuropathy and hearing impairment. In the pedigree the individual number, the age of the individual, and the WFS1 genotypes are depicted. The affected woman and her two sons (more ...)
All family members were examined in our outpatient clinic and medical history was taken. For all family members except patient II:2, the ophthalmological examinations included best corrected visual acuity measurements, slit-lamp microscopy and ophthalmoscopy. Goldmann perimetry was performed to evaluate visual field size. A morphometric analysis of the optic disc was performed using the Heidelberg Retina Tomograph II (HRT; Heidelberg Engineering, Heidelberg, Germany) [9
]. Color vision was assessed with the Hardy-Rand-Ritter (HRR) pseudoisochromatic plates, the Lanthony new color test, the Neitz anomaloscope (Neitz, Tokyo, Japan), and the standard pseudoisochromatic plates test. In addition, visually evoked potentials (VEP; Roland Consult, Brandenburg, Germany) were evaluated. Patient II:2 only underwent standard ocular examinations. All individuals underwent pure-tone audiometry and speech audiometry. Otoscopy was performed on all family members to rule out middle ear pathology. As part of a preoperative selection procedure for cochlear implantation, the proband also underwent electronystagmography, computed tomography (CT), and auditory steady-state response (ASSR) testing.
The affected family members underwent fasting serum testing to exclude diabetes mellitus (serum specific insulin, serum C-peptide and HbA1C were analyzed in the proband and plasma glucose was analyzed in all affected individuals).
Blood samples of all living individuals were collected in EDTA tubes and kept at room temperature. DNA was isolated within five days after withdrawal on a Chemagen MSM1 platform using the Chemagic DNA blood 10k kit (Chemagen, Baesweiler, Germany). Mutation analysis of WFS1 was performed by direct sequencing of the entire coding region (exon 2 to 8). The coding exons and the flanking intronic sequences were PCR amplified and subsequently sequenced on a 3730 automated sequencer using Dye terminator chemistry (Applied Biosystems, Foster City, CA). For primer information and PCR conditions see . In addition, OPA1 and three known LHON mutations (mtDNA positions m.11778, m.3460, and m.14484) were screened by a combination of dHPLC (Transgenomic, Inc., Omaha, NE) and direct sequencing analysis.