Cone Dysfunction Syndromes

Goodman, George; Ripps, Harris; Siegel, Irwin M.

doi:10.1001/archopht.1963.00960050216013

Cited by 137 publications

(52 citation statements)

References 28 publications

(5 reference statements)

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“…3 This total colorblindness is characterized by loss of color discrimination, low visual acuity, photophobia and nystagmus. [3][4][5][6] Rod monochromacy is inherited as an autosomal recessive trait with complete penetrance and is associated with mutations in four different genes. Two genes, CNGA3 and CNGB3, which are more frequently associated to achromatopsia, 7 encode the alpha and beta subunits of cyclic guanosine monophosphate-gated cation channel in cone cells, respectively.…”

Section: Introductionmentioning

confidence: 99%

Clinical and genetic investigation of a large Tunisian family with complete achromatopsia: identification of a new nonsense mutation in GNAT2 gene

Ouechtati

Merdassi²,

Bouyacoub

et al. 2010

J Hum Genet

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Complete achromatopsia is a rare autosomal recessive disease associated with CNGA3, CNGB3, GNAT2 and PDE6C mutations. This retinal disorder is characterized by complete loss of color discrimination due to the absence or alteration of the cones function. The purpose of the present study was the clinical and the genetic characterization of achromatopsia in a large consanguineous Tunisian family. Ophthalmic evaluation included a full clinical examination, color vision testing and electroretinography. Linkage analysis using microsatellite markers flanking CNGA3, CNGB3, GNAT2 and PDE6C genes was performed. Mutations were screened by direct sequencing. A total of 12 individuals were diagnosed with congenital complete achromatopsia. They are members of six nuclear consanguineous families belonging to the same large consanguineous family. Linkage analysis revealed linkage to GNAT2. Mutational screening of GNAT2 revealed three intronic variations c.119À69G4C, c.161+66A4T and c.875À31G4C that co-segregated with a novel mutation p.R313X. An identical GNAT2 haplotype segregating with this mutation was identified, indicating a founder mutation. All patients were homozygous for the p.R313X mutation. This is the first report of the clinical and genetic investigation of complete achromatopsia in North Africa and the largest family with recessive achromatopsia involving GNAT2; thus, providing a unique opportunity for genotype-phenotype correlation for this extremely rare condition.

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Section: Introductionmentioning

confidence: 99%

Clinical and genetic investigation of a large Tunisian family with complete achromatopsia: identification of a new nonsense mutation in GNAT2 gene

Ouechtati

Merdassi²,

Bouyacoub

et al. 2010

J Hum Genet

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“…Apart from complete forms of achromatopsia, several cases of incomplete achromatopsia have been described that are characterized by a residual ability to discriminate colors (Jäger, 1953;Goodman et al, 1963;Pokorny et al, 1979Pokorny et al, , 1982. The molecular basis of incomplete achromatopsia is, for the most part, unknown.…”

Section: Introductionmentioning

confidence: 99%

Molecular Basis of an Inherited Form of Incomplete Achromatopsia

Tränkner¹,

Jägle²,

Kohl³

et al. 2004

J. Neurosci.

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Mutations in the genes encoding the CNGA3 and CNGB3 subunits of the cyclic nucleotide-gated (CNG) channel of cone photoreceptors have been associated with autosomal recessive achromatopsia. Here we analyze the molecular basis of achromatopsia in two siblings with residual cone function. Psychophysical and electroretinographic analyses show that the light sensitivity of the cone system is lowered, and the signal transfer from cones to secondary neurons is perturbed. Both siblings carry two mutant CNGA3 alleles that give rise to channel subunits with different single-amino acid substitutions. Heterologous expression revealed that only one mutant forms functional channels, albeit with grossly altered properties, including changes in Ca 2ϩ blockage and permeation. Surprisingly, coexpression of this mutant subunit with CNGB3 rescues the channel phenotype, except for the Ca 2ϩ interaction. We argue that these alterations are responsible for the perturbations in light sensitivity and synaptic transmission.

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“…Esses achados são diferentes de outras distrofias maculares, nas quais a lesão predominante encontra-se na área macular, como a distrofia de cones (17) , doença de Stargardt, distrofia da Carolina do Norte e distrofia central areolar da coróide (7) . As dispersões pigmentares em pólo posterior são encontradas na retinite pigmentosa pericentral (inversa) e central (16) ou na distrofia reticular do epitélio pigmentado da retina de Sjögren, caracterizado por pigmento granular que migra em direção à periferia em formato de rede, que lembra redes de pesca com seus nós.…”

Section: Discussionunclassified