ERG Findings in Two Patients with Autosomal Dominant Congenital Stationary Night Blindness and His258Asn Mutation of the β-Subunit of Rod Photoreceptor CGMP-Specific Phosphodiesterase

Abstract

Recently, a missense mutation (His258Asn) has been identified in the β-subunit of rod cGMP-specific phosphodiesterase in a large multigeneration Danish family, in which autosomal dominant congenital stationary night blindness (adCSNB) is segregating. The mutation was shown to cosegregate with the disease phenotype. Here we report the ERG findings obtained on night blind members of two additional Danish families carrying an identical mutation. Electrophysiological findings are consistent with the hypothetical pathomechanism of a light-independent hyperpolarization of rod photoreceptors in CSNB. Variable expression of the mutation may account for individual differences in residual scotopic rod activity. Reports on impaired electroretinographic cone activity in cases of adCSNB might indicate genetic heterogeneity in adCSNB.