Electrophysiology and ocular blood flow in a family with dominant optic nerve atrophy and a mutation in the OPA1 gene.

OBJECTIVE

To characterize the clinical phenotype, with emphasis on electrophysiology and blood flow measurements, of a family with dominant optic nerve atrophy and an identified mutation in the OPA1 gene.

METHODS

Seven family members were examined. Ophthalmological evaluation included testing of visual acuity, ophthalmolscopy, kinetic perimetry, color vision testing, full-field electroretinography (ERG), multifocal electroretinography (MERG), and multifocal visual evoked potential (MVEP). Retrobulbar arterial blood flow and retinal capillary perfusion was measured in three patients using scanning laser Doppler flowmetry (SLDF) and color Doppler imaging techniques. PCR-SSCP and DNA sequencing determined the presence of a mutation in exon 18 of the OPA1 gene.

RESULTS

The clinical characteristics varied considerably in the family. The ERG and the MERG demonstrated normal retinal function, while the MVEP was abnormal in all examined patients. Retinal and optic nerve head capillary perfusion was significantly decreased in the three patients examined with SLDF. Retrobulbar blood flow velocities were significantly decreased in the central retinal and ophthalmic arteries. In all seven examined subjects, a microdeletion (1756-1767del(12 bp)) in the OPA1 gene was identified.

CONCLUSION

Patients with a mutation in the OPA1 gene have a very variable phenotype. MVEP and blood flow measurements are two new objective methods for an easier detection of this specific genetic optic nerve atrophy.