X-linked Retinoschisis Associated with Retinitis Punctata Albescens Caused by a Mutation in the RS1 Gene: A Family Study

Purpose: To describe the clinical and genetic characteristics (mutation in RS1 gene) of a Spanish family with X-linked retinoschisis (XLRS) associated with retinitis punctata albescens (RPA). Methods: The detailed ophthalmological examination included best corrected visual acuity (BCVA), colour and autofluorescence photography, fluorescein angiography, optical coherence tomography and electrophysiology tests. A next-generation sequencing (NGS) strategy was applied to the index patient, and then sequenced in an Illumina NextSeq500 system. Candidate variants considered to be disease-causing in the patient were confirmed and segregated in the family by Sanger sequencing. Results: We have studied three siblings of 54, 59 and 50 years old. Two of them presented with macular foveoschisis and a whitish mottling of the pigment epithelium in the peripheral and equatorial retina, while the other had macular atrophy. Electroretinography revealed a reduced b-wave, while a-wave remained unchanged. Mutation in RS1 (c.98G>A; p.Trp33*) was identified as the cause of the disease. Conclusion: XLRS is a genetic disease that leads to irreversible visual loss. We describe an unusual phenotype manifestation of a known mutation.

A PRPH2 gene variant detected in retinitis punctata albescens with congenital hypertrophy of the retinal pigment epithelium

Retinitis punctata albescens (RPA) is generally diagnosed by the presence of numerous clusters of white punctate lesions in the retina that progress over time and are related to several gene variants. The multifocal variant of congenital hypertrophy of the retinal pigment epithelium (CHRPE) is characterized by multiple, grouped, sharply circumscribed, pigmented spots. The PRPH2 gene encodes a photoreceptor-specific glycoprotein, which is essential for the morphogenesis of rod and cone photoreceptor outer segments. A 39-year-old Chinese female with nyctalopia, complained about blurred vision, presented a unique co-existing feature of RPA and CHRPE. Dilated fundus exam demonstrated numerous porcelain white discrete dots in both eyes and multiple, small, flat clusters of round brown to black pigmented lesions in the left eye. The full field electroretinography (ERG) showed decreased responses after standard dark adaptation and normal b-wave amplitudes after a long (4-h) dark-adapted period. A heterozygous PRPH2 splicing variant was detected in the proband. In addition, the same variant was found in her mother, her son, and her daughter. We describe a PRPH2 variant in a rare case of RPA associated with multifocal CHRPE of the same individual.

A novel homozygous frameshift variant in the cellular retinaldehyde-binding protein 1 (RLBP1) gene causes retinitis punctata albescens

Background Retinitis punctata albescens is a form of retinitis pigmentosa characterized by white fleck-like deposits in the fundus, in most cases caused by pathogenic variants in RLBP1 gene. The purpose of this work is to report the phenotypic and genotypic data of a patient with retinitis punctata albescens carrying a deletion in the RLBP1 gene. Results An 8-year-old Caucasian female has been complaining of nyctalopia for the last 2 years. No other ocular symptoms were present. No relevant past medical or familiar history was described. At clinical examination, the patient’s best-corrected visual acuity was 20/20 in both eyes. Anterior segment evaluation and intraocular pressure were normal in both eyes. At fundoscopy, multiple punctate whitish-yellow fleck-like lesions were observed in the proximity of temporal superior and inferior vascular arcades. Scotopic electroretinogram demonstrated severely reduced rod response, without improvement or recovery of rod system function after prolonged dark adaptation. Blood DNA samples of this patient and from her parents were screened for causal variants in RLBP1, RDH5, and PRPH2. Conclusion A probable pathogenic frameshift variant was identified in homozygosity in the RLBP1 gene with an autosomal recessive transmission as another cause of retinitis punctata albescens. This DNA variant will aid ongoing functional studies and add to our understanding of the molecular pathology about RLBP1-associated retinopathies.