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congenital stationary night blindness type 1B (CSNB1B)
Genetics:
- autosomal recessive
- associated with defects defects in GRM6
Clinical manifestations:
- patients are night blind from an early age
- when maximally dark-adapted, they can perceive lights only with an intensity equal to or slightly dimmer than that normally detected by the cone system.
Special laboratory:
- negative electroretinogram (ERG) waveform
- ERGs in response to single brief flashes of light have clearly detectable a-waves, which are derived from photoreceptors, & greatly reduced b-waves, which are derived from the second-order inner retinal neurons
- ERGs in response to sawtooth flickering light indicate a markedly reduced ON response & a nearly normal OFF response
- no subjective delay in the perception of suddenly appearing white vs black objects on a gray background
General
congenital stationary night blindness type 1 (CSNB1)
Database Correlations
OMIM 257270
References
OMIM :accession 257270