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Retinal cone photoreceptors mediate fine visual acuity, daylight vision, and color vision. Congenital hereditary conditions in which there is a lack of cone function in humans cause achromatopsia, an autosomal recessive trait, characterized by low vision, photophobia, and lack of color discrimination. Herein we report the identification of mutations in the PDE6C gene encoding the catalytic subunit of the cone photoreceptor phosphodiesterase as a cause of autosomal recessive achromatopsia. Moreover, we show that the spontaneous mouse mutant cpfl1 that features a lack of cone function and rapid degeneration of the cone photoreceptors represents a homologous mouse model for PDE6C associated achromatopsia.

Cone dystrophy with supernormal rod response (CDSRR) is a retinal disorder characterized by reduced visual acuity, color vision defects, and specific alterations of ERG responses that feature elevated scotopic b-wave amplitudes at high luminance intensities. Mutations in PDE6H and in KCNV2 have been described in CDSRR. A combined clinical and genetic study was conducted in a cohort of patients with CDSRR, to substantiate these priorSeventeen patients from 13 families underwent a detailed ophthalmic examination including color vision testing, Goldmann visual fields, fundus photography, Ganzfeld and multifocal ERGs, and optical coherence tomography. The coding sequences and flanking intron/UTR sequences of PDE6C and KCNV2 were screened for mutations by means of DHPLC and direct DNA sequencing of PCR-amplified genomic DNA. results. Whereas no mutations were detected in the PDE6H gene, mutations in KCNV2 were identified in all patients, in either the homozygous or compound heterozygous state. Ten of the 11 identified mutations were novel, including three missense and six truncating mutations and one gross deletion. The mutations concordantly segregate in all available families according a recessive mode of inheritance. The CDSRR phenotype was associated with reduced visual acuity of variable degree and color vision defects. Macular defects ranging from mild pigmentary changes to distinct foveal atrophy were present in nine patients. Progression of the disease was observed in only three of seven patients with follow-up data.The phenotype of cone dystrophy with supernormal rod response is tightly linked with mutations in KCNV2.

International audience; Scanning-laser ophthalmoscopy is a technique for confocal imaging of the eye in vivo. The use of lasers of different wavelengths allows to obtain information about specific tissues and layers due to their reflection and transmission characteristics. In addition, fluorescent dyes excitable in the blue and infrared range offer a unique access to the vascular structures associated with each layer. In animal models, a further enhancement in specificity can be obtained by GFP expression under control of tissue-specific promotors. Important fields of application are studies in retinal degenerations and the follow-up of therapeutic intervention.