Abstract
Purpose:
To describe retinal patterns in patients with Usher syndrome type III (USH3) caused by mutations in the Clarin 1 gene (CLRN1).
Methods:
All patients underwent in-depth phenotype examination, including visual acuity testing (EDTRS), color vision (Panel D15 saturated and desaturated), visual field testing, spectral domain optical coherence tomography and fundus autofluorescence (SD-OCT and FAF, Spectralis, Heidelberg, Germany), en-face AO imaging (Imagine Eyes, Orsay, France), field electroretinography (ERG) and multifocal electroretinogram (mfERG) were used to record retinal functional output.
Results:
CLRN1 mutations were present in all 6 patients. The retinitis pigmentosa followed rod-cone degeneration pattern in all patients. Age range at the time of examination was 2 to 53 maturation years. Male and female ratio was 2/4, respectively. Night blindness noticed in the mean 14 years of age, hearing problems appeared by the mean of 4 years of age. Mean visual acuity was 20/32. No color vision defects were found. Both cone and rods full field ERG was abolished and mfERG waves were not reproducible. Central visual field was constricted to 4 degree. The mean of central macula thickness was 264±150 microns with cystic changes and significant shortening of inner segment ellipsoid band on SD-OCT images. Irregular cone mosaic patterns were present at AO images.
Conclusions:
Detailed retina phenotype description was performed in Usher syndrome type III (USH3) caused by mutations in the Clarin 1 gene. Patients represent with relatively late disease onset, advanced retinal structure and function related changes, although preserved visual perception capabilities.
Keywords: 696 retinal degenerations: hereditary •
461 clinical (human) or epidemiologic studies: natural history •
539 genetics