Characterization of the Genotype and Phenotype of Congenital Stationary Night Blindness in Atlantic Canada

Abstract

Abstract: : Purpose: To present the spectrum of clinical manifestation of congenital stationary night blindness (CSNB) in families from Atlantic Canada, and to determine the genetic mutation causing the disease in each family. From this information, to determine if there is a correlation between the type and/or location of the mutation and the clinical manifestations of CSNB. Methods: Charts of patients with complete CSNB (cCSNB) or incomplete CSNB (iCSNB) seen at the IWK Health Centre over the past 15 years were reviewed. Diagnosis was based on clinical features and electroretinography (ERG) findings. To determine the mutation responsible for their disease, a sample from each affected individual is obtained for genetic analysis. Results: To date, clinical data is available on 23 individuals with iCSNB from 12 families, and 4 singleton cases of cCSNB. ERG characteristics were consistent within both iCSNB and cCSNB groups. Among iCSNB patients, visual acuity ranged from 6/9 to 6/48, with myopia present in 73% of cases (-1.00 to -16.75). All individuals manifested optic disc pallor to some degree, while other features within the disease spectrum showed greater variability. The causative mutation in six families with iCSNB has been identified thus far. Conclusions: Among affected individuals with iCSNB, some features were consistent whereas others showed considerable variability. This may relate to the mechanism of dysfunction of the causative gene due to different mutations. Correlation of these mutations with the clinical features of affected individuals will give further information on the role of the genetic abnormality in the disease.

Keywords: retina • genetics • clinical (human) or epidemiologic studies: pre