Clinical and Genetic Characteristics of Chinese Patients with Occult Macular Dystrophy

New recessive compound heterozygous variants of RP1L1 in RP1L1 maculopathy

AIM

To identify a maculopathy patient caused by new recessive compound heterozygous variants in RP1L1.

METHODS

Comprehensive retinal morphological and functional examinations were evaluated for the patient with RP1L1 maculopathy. Targeted sequence capture array technique was used to screen potential pathologic variants. Polymerase chain reaction and Sanger sequencing were used to confirm the screening results.

RESULTS

Fundus examination showed round macular lesions appeared in both eyes. Optical coherence tomography showed that the inner segment/outer segment continuity was disorganized and disruptive in the left eye, but it was uneven and slightly elevated in the right eye. Fundus autofluorescence showed patchy hyper-autofluorescence in the macula. Visual field examination indicates central defects in both eyes. Electroretinogram (ERG) and multifocal ERG showed no obvious abnormalities. Fundus fluorescein angiography in the macula showed obviously irregular hyper-fluorescence in the right eye and slightly hyper-fluorescence in the left eye. We found that the proband carried a missense variant (c.1972C>T) and a deletion variant (c.4717_4718del) of RP1L1, which were originated from the parents and formed compound heterozygous variants. Both variants are likely pathogenic according to the ACMG criteria. Multimodal imaging, ERG and detailed medical history are important diagnostic tools for differentiating between acquired and inherited retinal disorders.

CONCLUSION

A maculopathy case with detailed retinal phenotype and new recessive compound heterozygous variants of RP1L1 is identified in a Chinese family, which expands the understanding of phenotype and genotype in RP1L1 maculopathy.

Occult Macular Dysfunction Syndrome: Identification of Multiple Pathologies in a Clinical Spectrum of Macular Dysfunction with Normal Fundus in East Asian Patients: EAOMD Report No. 5

Occult macular dystrophy (OMD) is the most prevalent form of macular dystrophy in East Asia. Beyond RP1L1, causative genes and mechanisms remain largely uncharacterised. This study aimed to delineate the clinical and genetic characteristics of OMD syndrome (OMDS). Patients clinically diagnosed with OMDS in Japan, South Korea, and China were enrolled. The inclusion criteria were as follows: (1) macular dysfunction and (2) normal fundus appearance. Comprehensive clinical evaluation and genetic assessment were performed to identify the disease-causing variants. Clinical parameters were compared among the genotype groups. Seventy-two patients with OMDS from fifty families were included. The causative genes were RP1L1 in forty-seven patients from thirty families (30/50, 60.0%), CRX in two patients from one family (1/50, 2.0%), GUCY2D in two patients from two families (2/50, 4.0%), and no genes were identified in twenty-one patients from seventeen families (17/50, 34.0%). Different severities were observed in terms of disease onset and the prognosis of visual acuity reduction. This multicentre large cohort study furthers our understanding of the phenotypic and genotypic spectra of patients with macular dystrophy and normal fundus. Evidently, OMDS encompasses multiple Mendelian retinal disorders, each representing unique pathologies that dictate their respective severity and prognostic patterns.

The role of near-infrared reflectance imaging in retinal disease: A systematic review

Near-infrared reflectance (NIR) retinal imaging aids in a better visualization of structures at the level of outer retina, retinal pigment epithelium, and choroid. It has multiple advantages, including easy acquisition in association with structural spectral domain optical coherence tomography, more comfort for patients, and enhanced contrast and spatial resolution. It helps in the diagnosis of chorioretinal diseases that present with minimal funduscopic findings and can be used to follow up many chorioretinal conditions. We describe the chorioretinal NIR imaging appearance and the clinical role of NIR imaging in ocular inflammatory disease, vascular and acquired disease, degenerative disease, tumors, associated systemic condition, toxic and traumatic disease, optic nerve head conditions, and physiological findings.

Occult Macular Dystrophy: a case report and major review

BACKGROUND

Occult Macular Dystrophy (OMD), a rare autosomal dominant disorder caused by mutations in the retinitis pigmentosa 1-like protein 1 gene (RP1L1), is characterized by loss of central visual acuity in the absence of fundoscopic abnormalities. In patients suspected of having OMD based on unexplained central vision loss and/or photophobia, changes may be detected with spectral-domain optical coherence tomography. Subsequently, the diagnosis can be confirmed with genetic analysis.We report a case of an 18-year-old White male whose suspected diagnosis of OMD was confirmed by molecular testing. We conducted an extensive review of the literature of previously reported patients with OMD to date.

METHODS

A PubMed search of "RP1L1 and Occult Macular Dystrophy" revealed 34 papers. There were 225 individuals with genetically confirmed, symptomatic OMD; an additional 15 had a confirmed mutation but were asymptomatic and discovered incidentally.

RESULTS

Our patient presented with a 10-year history of unexplained loss of central visual acuity and photophobia. Genetic analysis confirmed the presence of a p.R45W substitution on the RP1L1 gene, the most common pathologic mutation in OMD.

CONCLUSIONS

Due to the lack of appreciable fundoscopic changes, correct identification of the disease can be difficult. Incomplete penetrance has been associated with the condition, and the age of onset is highly variable. Much of the research discussing OMD has come from Eastern Asia, but whether this is due to a heightened awareness and screening protocols, or increased incidence is unclear. Additional research and increased awareness globally will help with more timely and accurate diagnoses.

Genotypic spectrum and phenotype correlations of EYS-associated disease in a Chinese cohort

Background

To date, certain efforts have been made to investigate the clinical and genetic characteristics of patients with EYS mutations. However, data for Chinese patients are limited.

Objectives

To perform a detailed phenotyping and genetic characterization of 55 Chinese patients with EYS-RD, and to identify risk factors for these clinical data.

Methods

A total of 55 patients with EYS-RD were recruited. Best-corrected visual acuity (BCVA), patient age, age at symptom onset, disease duration, and genetic information were collected.

Results

Thirty-six novel variants, three hot mutations of EYS (30.3%, c.6416G>A, c.6557G>A, c.7492G>C) and one hot region (49.06%, Laminin G domains) were identified. In all, 36.84% of the mutations occurred at base G site, and majority of mutations (56.56%) were missense. Late-truncating mutations are significantly more prevalent (41.30%). The mean age of onset was 15.65 ± 14.67 years old; it had no significant correlation with genotype. The average BCVA was 0.73 ± 0.93 LogMAR, and 61.8% of eyes had a BCVA better than 0.52 logMAR. BCVA was positively correlated with disease duration time. The mean MD was 23.18 ± 7.34 dB, MD showed a significant correlation with genotype and age. Cataract was present in 56.45% of patients, and 42.59% of patients showed an absence of pigmentation in the retina. Cataract and hyperpigmentation both showed a significant correlation with age.

Conclusions

EYS-RD is associated with a moderate phenotype with onset around adolescence, but great variability. Our study largely enhances the current knowledge of phenotypic and genotypic characteristics of EYS-RD, which could pave the way for better management of these patients.

Near-Infrared Reflectance Imaging in Retinal Diseases Affecting Young Patients

Near-infrared reflectance (NIR) is a noninvasive, contactless, and rapid in vivo imaging technique for visualizing subretinal alterations in the photoreceptor layer, retinal pigment epithelium, and choroid. The present report describes the application of this imaging method in retinal and choroidal pathologies affecting young patients where scarce cooperation, poor fixation, and intense glare sensation can result in a challenging clinical examination. A literature search of the MEDLINE database was performed using the terms "near-infrared reflectance" and "spectral-domain optical coherence tomography." Articles were selected if they described the diagnostic use of NIR in children or young adults. Of 700 publications, 42 manuscripts published between 2005 and 2020 were inherent to children or young adults and were considered in this narrative literature review. The first disease category is the phakomatoses where NIR is essential in visualizing choroidal alterations recognized as cardinal biomarkers in neurofibromatosis type 1, microvascular retinal alterations, and retinal astrocytic hamartomas. Another diagnostic application is the accurate visualization of crystals of various nature, including the glistening crystals that characterize Bietti crystalline dystrophy. Acute macular neuropathy and paracentral acute middle maculopathy represent a further disease category with young adulthood onset where NIR is not only diagnostic but also essential to monitor disease progression. A further interesting clinical application is to facilitate the detection of laser-induced maculopathy where funduscopic examination can be normal or subnormal. In conclusion, NIR imaging has a noninterchangeable role in diagnosing certain retinal diseases, especially in children and young adults where there is scarce collaboration and a lack of evident clinical findings. Moreover, this technique can reveal unique retinal and choroidal biomarkers highly specific to rare conditions.