CSNB1D is an autosomal recessive form of congenital stationary night blindness that is characterized by a Riggs type of electroretinogram (proportionally reduced a- and b-waves). Patients with Riggs-type CSNB have visual acuity within the normal range and no ... CSNB1D is an autosomal recessive form of congenital stationary night blindness that is characterized by a Riggs type of electroretinogram (proportionally reduced a- and b-waves). Patients with Riggs-type CSNB have visual acuity within the normal range and no symptoms of myopia and/or nystagmus (summary by Riazuddin et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of congenital stationary night blindness, see CSNB1A (310500).
Riazuddin et al. (2010) studied 5 affected individuals from 4 sibships of a large consanguineous Pakistani pedigree from the Punjab province who reported night blindness with normal daytime vision since early childhood. Detailed ocular examination in 4 of ... Riazuddin et al. (2010) studied 5 affected individuals from 4 sibships of a large consanguineous Pakistani pedigree from the Punjab province who reported night blindness with normal daytime vision since early childhood. Detailed ocular examination in 4 of the 5 individuals revealed no obvious anomalies on funduscopic examination, with no macular atrophy, no pigment deposition, and no vascular attenuation. Full-field ERGs showed absence of a- and b-waves under scotopic conditions for all 4 patients examined; in 2 of the patients, cone responses were modestly reduced under photopic conditions, whereas in the other 2 patients, cone responses were indistinguishable from those of an unaffected family member. Riazuddin et al. (2010) stated that the appearance of the fundus together with the ERG results of rod response were strongly suggestive of CSNB with a Riggs type of ERG, which previously had been described in only a few patients with an autosomal dominant form of CSNB.
In affected members of a large consanguineous Pakistani pedigree with CSNB mapping to chromosome 15q22.2-q26.1, Riazuddin et al. (2010) analyzed candidate genes and identified homozygosity for a 2-bp deletion in the SLC24A1 gene (603617.0001). The mutation segregated with ... In affected members of a large consanguineous Pakistani pedigree with CSNB mapping to chromosome 15q22.2-q26.1, Riazuddin et al. (2010) analyzed candidate genes and identified homozygosity for a 2-bp deletion in the SLC24A1 gene (603617.0001). The mutation segregated with disease in the family and was not found in 384 control chromosomes from the Punjab province of Pakistan or in 192 chromosomes of northern European descent. Riazuddin et al. (2010) analyzed the SLC24A1 gene in another 16 probands with CSNB but found no additional pathogenic mutations.