ConeRodDystrophie

Cone-Rod Dystrophy (ConeRodDystrophie) is a rare inherited retinal dystrophy characterized by early dysfunction of cone photoreceptors followed by progressive degeneration of rods, leading to central vision loss and eventual peripheral vision impairment. The condition affects color vision and visual acuity more than night vision in the early stages, with night blindness often developing as the disease advances. Onset typically occurs in childhood or adolescence but can present in adulthood in some cases. The progression is variable, with some individuals maintaining relatively good peripheral vision for years.

Genetics: Cone-Rod Dystrophy shows substantial genetic heterogeneity and can follow autosomal dominant, autosomal recessive, or X-linked inheritance. More than a dozen genes have been implicated, including ABCA4, PRPH2, PROM1, CRX, and C1QTNF5. Mutations in these genes disrupt photoreceptor structure or function, leading to the cone-first pattern characteristic of CRD. Genetic testing can confirm the diagnosis and guide counseling.

Clinical features and diagnostics: Patients typically present with reduced central vision, diminished color discrimination, photophobia, and variable refractive errors. Fundus examination may reveal macular atrophy or pigmentary changes, or bull's-eye patterns. Optical coherence tomography shows macular thinning and disruption of the outer retinal layers. Electroretinography demonstrates impaired cone function early, with subsequent rod dysfunction.

Management and outlook: There is no cure for Cone-Rod Dystrophy. Management focuses on low-vision support, visual aids, and safety precautions. Regular monitoring, management of complications, and genetic counseling are recommended. Research into gene therapy and other disease-modifying approaches is ongoing, with several trials addressing related inherited retinal dystrophies.

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