Retinal ciliopathy due to mutation in Usher gene

Retinal ciliopathy due to mutation in Usher gene (Orphanet code 156177) refers to a group of inherited retinal dystrophies caused by mutations in genes typically associated with Usher syndrome, but presenting primarily or exclusively with retinal involvement (retinitis pigmentosa) without the sensorineural hearing loss that characterizes classic Usher syndrome. Usher syndrome genes encode proteins critical for the structure and function of cilia in photoreceptor cells and hair cells of the inner ear. When mutations in these genes selectively or predominantly affect retinal photoreceptor cilia, patients develop progressive rod-cone dystrophy (retinitis pigmentosa) leading to night blindness, progressive visual field constriction, and eventual central vision loss, while hearing may be normal or only mildly affected. The retinal degeneration in this condition results from dysfunction of the photoreceptor connecting cilium, which is essential for transporting proteins between the inner and outer segments of rod and cone cells. Affected individuals typically present with nyctalopia (night blindness) in childhood or adolescence, followed by progressive peripheral visual field loss and eventual decline in central visual acuity. Fundoscopic examination reveals characteristic bone-spicule pigmentation, attenuated retinal vessels, and waxy pallor of the optic disc. Electroretinography (ERG) shows diminished or absent rod and cone responses. Currently, there is no curative treatment for this condition. Management is primarily supportive and includes regular ophthalmologic monitoring, low-vision aids, orientation and mobility training, and genetic counseling. Vitamin A supplementation has been suggested in some forms of retinitis pigmentosa, though evidence remains limited. Gene therapy approaches are under active investigation for several forms of Usher-related retinal disease, and clinical trials are ongoing for specific gene targets. Patients should also be monitored for potential subclinical hearing changes given the involvement of Usher syndrome genes.

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