Abstract
Purpose: :
Retinitis pigmentosa (RP) is a group of inherited retinal diseases characterized by night blindness, visual field defects, and loss of visual acuity caused by photoreceptor degeneration. Both genetically and clinically, RP is highly heterogeneous. Here, we aim to identify clinical features that might be distinct for a specific genetic subtype, and hence to improve genotype-phenotype correlations for autosomal recessive RP (arRP).
Methods: :
In 100 RP patients with an unknown genetic cause of disease, next-generation sequencing (NGS) was performed to simultaneously analyze 110 known retinal dystrophy genes. Mutations were confirmed via Sanger sequencing. Patients that were shown to carry mutations in IMPG2 underwent detailed clinical examination that included ophthalmologic examination, kinetic perimetry, fundus photography, spectral-domain optical coherence tomography (OCT), auto fluorescence imaging and full-field and multifocal electroretinography (ERG).
Results: :
The IMPG2 gene was recently identified as a cause of arRP. In one of the families that were originally reported with mutations in IMPG2, affected individuals showed a bull’s eye maculopathy with typical RP findings in the periphery. In one of the 100 probands that were analyzed with NGS, novel compound heterozygous mutations were identified (c.3423-8_3423-5del and p.Arg127X), which were also found in her affected brother. The two affected siblings (aged 59 and 60) showed typical signs of RP, with a severe loss of rod-cone function on ERG, an age of onset before 20 years, and a relatively spared visual acuity. Interestingly, both patients also showed signs of a bull’s eye maculopathy.
Conclusions: :
This study indicates that a bull’s eye maculopathy might be a distinctive feature in arRP patients with mutations in IMPG2.
Keywords: retinal degenerations: hereditary • genetics