The RPGRIP1-related retinal phenotype in children

To characterise the childhood retinal phenotype associated with recessive mutations in retinitis pigmentosa GTPase regulator interacting protein 1 (RPGRIP1), a gene that has been infrequently associated with Leber congenital amaurosis, the most severe form of childhood non-syndromic retinal dystrophy.

This was a retrospective case series analysis.

Nine children (seven families) with homozygous RPGRIP1 mutations were identified. All were noted by their families to have had shaking eyes, variable eye turn and/or poor vision at or soon after birth and to be more comfortable in darkness than daylight. At the age of examination (2-7 years of age) fixation was poor or non-existent with hemeralopia, nystagmus, variable strabismus and often an oculodigital sign (6/9). Electroretinography was non-recordable. The posterior pole was grossly normal with mild vascular attenuation, but one girl did have a subtle abnormal macular reflex associated with decreased autofluorescence. Retinal pigment epithelium changes were seen in the periphery, ranging from mottling to bone spicules, and cycloplaegic refraction was hyperopic (+3 to +10 diopters). Two children were photophobic and two were developmentally delayed. One boy had oesotropia and nystagmus that decreased when hyperopic spectacles were worn. One girl decreased her nystagmus amplitude by adopting a particular gaze preference.

Recessive RPGRIP1 mutations cause a severe cone-rod Leber congenital amaurosis phenotype, often with poor or no fixation and an oculodigital sign. In the first decade of life retinal changes are clinically most evident in the periphery. Despite the typical severity of the phenotype, fixation can improve for some affected children with wear of the associated hyperopic refraction or by a null point that dampens nystagmus. Spectacle correction of high refractive errors should be encouraged.