autosomal recessive

The distinctive feature of Oguchi disease is the peculiar and distinctive discoloration of the fundus under various light conditions, known as the Mizuo phenomenon.  Typically, the fundus assumes a golden or gray-white coloration under light adapted conditions but this disappears during acute dark adaptation and only reappears after prolonged time spent in darkness.  Rod dark adaptation is markedly delayed while that of cones is normal.  Visual acuity, visual fields and color vision are all normal.   A- and b-waves on single flash ERG are decreased or absent under lighted conditions but increase after prolonged dark adaptation.  Night blindness is present from birth without progression.

Night blindness is a feature of many pigmentary and other retinal disorders, most of which are progressive.  However, there is also a group of genetically heterogeneous disorders, with generally stable scotopic defects and without RPE changes, known as congenital stationary night blindness (CSNB).  At least 10 mutant genes are responsible with phenotypes so similar that genotyping is usually necessary to distinguish them.  All are caused by defects in visual signal transduction within rod photoreceptors or in defective photoreceptor-to-bipolar cell signaling with common ERG findings of reduced or absent b-waves and generally normal a-waves.  The photopic ERG is usually abnormal to some degree as well and visual acuity may be subnormal.  In the pregenomic era, subtleties of ERG responses were frequently used in an attempt to distinguish different forms of CSNB.  Genotyping now enables classification with unprecedented precision.

Congenital stationary night blindness disorders are primarily rod dystrophies presenting early with symptoms of nightblindness and relative sparing of central vision.  Nystagmus and photophobia are usually not features.  Dyschromatopsia and loss of central acuity can develop later as the cones eventually become dysfunctional as well but these symptoms are much less severe than those seen in cone-rod dystrophies.  The amount of pigmentary retinopathy is highly variable. 

In this disorder (CSNB1C) the b-wave responses are severely deficient (no scotopic response) and a-waves seem to be normal.  Some reduction in central acuity is common.  High myopia may be present together with nystagmus and strabismus.  In one family, hypoplastic discs and relative thinning of the inner nuclear layer were described in twin brothers.  ERG responses suggest loss of ON bipolar cell function similar to that found in patients with GRM6 mutations (CSNB1B; 257270).

Night blindness is a feature of many pigmentary and other retinal disorders, most of which are progressive.  However, there is also a group of genetically heterogeneous disorders, with generally stable scotopic defects, known as congenital stationary night blindness (CSNB).  At least 10 mutant genes are responsible with phenotypes so similar that genotyping is usually necessary to distinguish them.  All are caused by defects in visual signal transduction within rod photoreceptors or in defective photoreceptor-to-bipolar cell signaling with common ERG findings of reduced or absent b-waves and generally normal a-waves.  However, the photopic ERG can be abnormal to some degree as well and visual acuity may be subnormal.  In the pregenomic era, subtleties of ERG responses were frequently used in an attempt to distinguish different forms of CSNB.  Genotyping now enables classification with unprecedented precision.

Congenital stationary night blindness disorders are primarily rod dystrophies presenting early with symptoms of nightblindness and relative sparing of central vision.  Nystagmus and photophobia are usually not features.  Dyschromatopsia and loss of central acuity can develop later as the cones eventually become dysfunctional as well but these symptoms are much less severe than those seen in cone-rod dystrophies.  The amount of pigmentary retinopathy is highly variable.

In this disorder (CSNB1B) the b-wave responses are severely deficient and a-waves seem to be normal.  Color vision is normal and refractive errors are unremarkable.  Visual acuity ranges from normal to a mild reduction (20/15-20/40).  One patient with 20/40 vision has been reported to have bone spicule pigment clumps in the midperiphery. Several patients with subnormal vision have been reported to have nystagmus.

Patients have a distinctive ERG pattern response to scotopic 15-Hz flicker stimuli that suggest that more than two rod neural pathways exist.

Congenital cataracts are one of the cardinal features of Marinesco-Sjogren syndrome but lens opacities may have a later onset and may be progressive as well.  Strabismus and nystagmus are sometimes present.

Cataracts, microphthalmia, and microcornea (mean diameter ~7.5 mm) are present at birth and precede the onset of neurological symptoms.  The lens opacities often consist of anterior and posterior subcapsular opacities but the entire lens may be opaque as well.  Some adults have bilateral ptosis.  The pupils are often small and have sluggish responses to light and mydriatics.  Strabismus and horizontal pendular nystagmus are common.  Visual impairment may be severe.

Patients have been reported with juvenile and infantile cataracts.  Reported prevalence varies possibly because the diagnostic criteria have not been established and more than one disorder may be represented by the title.  Rothmund (an ophthalmologist) originally reported two families of 5 children in which lens opacities were found, but Thomson, who was a dermatologist, in a later report did not mention cataracts.  The lens opacities are usually nuclear or posterior cortical in location and may be evident in 50% of patients.  Iris stromal changes such as hypoplasia have also been reported.  Eyelashes and/or eyebrows may be sparse.  This is likely the same disorder as the previously described ‘mesodermal dysgenesis of the iris and skeletal dysplasia’ and formerly listed as 270240 in OMIM.