Journal of Clinical and Experimental Ophthalmology
Open Access

Abstract

A Novel NYX Mutation Associated with X-Linked Congenital Stationary Night Blindness in a New Zealand Family

Monika A Pradhan, Dianne M Sharp, Justin S Mora, Mariana Wittmer, Wolfgang Berger and Andrea L Vincent

Background: Complete Congenital Stationary Night Blindness (CSNB) type 1A is an X-linked condition associated with reduced scotopic vision, myopia, nystagmus and mutations in the NYX (nyctalopin) gene. This paper reports a novel mutation identified in this gene associated with X-linked CSNB in a New Zealand Caucasian family.
Methods: A 16 year old male, presenting with night blindness, underwent detailed phenotypic assessment including pedigree construction and electrophysiology testing. Genetic analysis was performed in the Division of Medical Molecular Genetics, University of Zurich, Switzerland. Other family members also underwent clinical examination and genetic testing.
Results: Electrodiagnostic testing has confirmed the diagnosis of Type 1 (complete) CSNB in the proband and his maternal grandfather by identifying a 'negative' rod-mediated waveform and near normal cone responses.
NYX gene testing revealed a novel missense sequence alteration c.425T>G (p.Leu142Arg) in the proband. This has not been detected in control European and New Zealand Caucasian populations and segregates with the disease in this family.
Conclusion: Missense changes account for the majority of the mutations reported in the NYX gene so far. A novel missense sequence variant causing complete CSNB has been identified in a New Zealand family. This expands the known mutation spectrum of the NYX gene.