Next generation sequencing in the diagnosis of Stargardt's disease

Stem Cell Ophthalmology Treatment Study (SCOTS): Bone Marrow-Derived Stem Cells in the Treatment of Stargardt Disease

Background: Stargardt Disease is the most common inherited macular degeneration, typically resulting in progressive central vision loss and legal blindness at an early age. We report regarding 34 eyes with Stargardt Disease treated in the Stem Cell Ophthalmology Treatment Study (SCOTS and SCOTS2). Methods: Autologous bone marrow was processed, separating the stem cell fraction which was provided Arms using retrobulbar, subtenons, intravitreal or subretinal and intravenous. The follow-up period was one year. Results: Of the 34 treated eyes, 21 (61.8%) improved, 8 (23.5%) remained stable, and 5 (14.7%) showed continued progression of their disease. Results were statistically significant with p = 0.0004. The average central vision improvement following treatment was 17.96% (95%CI, 16.39–19.53%) and ranged up to 80.5%. Of 17 patients treated, 13 (76.5%) showed visual acuity improvement in one or both eyes, 3 patients (17.6%) showed no net loss, and 1 worsened as a consequence of disease progression; 94.1% of patients had improved vision or remained stable. There were no adverse events. Conclusions: Patients with Stargardt Disease may potentially benefit from autologous bone marrow-derived stem cells (BMSC) as provided in SCOTS. Improvement or stabilization of vision was found to occur for the vast majority of reported patients and findings were highly statistically significant.

Retinal dystrophies with bull's-eye maculopathy along with negative ERGs

PURPOSE

The aim of this study was to examine the ophthalmological characteristics and genotypes of patients with congenital retinal pathologies, who display a bull's-eye maculopathy in the fundus, along with a negative scotopic electroretinogram.

METHODS

We analysed the results of five patients showing both a bull's-eye maculopathy, as well as a negative scotopic ERG evoked by a bright flash. Their median age was 39 years (range 11-63 years): three males and two females. All underwent a comprehensive examination with determination of distant visual acuity (ETDRS) and recording of the full-field ERG (scotopic and photopic). Fundus, OCT, and FAF images were obtained, the kinetic visual field was determined, and colour vision (D-15) was tested in most patients. Targeted gene panel sequencing was performed on peripheral blood.

RESULTS

One patient carried a homozygous ABCA4 mutation and an additional heterozygous variant in CRX. Two of the five patients were shown to have a heterozygous mutation in the CRX gene, one of whom had an additional heterozygous ABCA4 mutation. Two patients had the common heterozygous mutation c.2413G>A;p.Arg838His in GUCY2D. In all of the patients, there was a reduction in the amplitude of the b-wave with a regular a-wave amplitude in the scotopic bright-flash ERG.

CONCLUSIONS

The five patients with bull's-eye maculopathy along with a negative ERG had differing genotypes. Mutations were found in the CRX gene (2 patients), the ABCA4 gene (1 patient), and the GUCY2D gene (2 patients).

Identification of novel pathogenic ABCA4 variants in a Han Chinese family with Stargardt disease

Stargardt disease (STGD1, OMIM 248200) is a common hereditary juvenile or early adult onset macular degeneration. It ultimately leads to progressive central vision loss. Here, we sought to identify gene mutations associated with STGD1 in a three-generation Han Chinese pedigree by whole exome sequencing and Sanger sequencing. Two novel potentially pathogenic variants in a compound heterozygous state, c.3607G>T (p.(Gly1203Trp)) and c.6722T>C (p.(Leu2241Pro)), in the ATP binding cassette subfamily A member 4 gene (ABCA4) were identified as contributing to the family’s STGD1 phenotype. These variants may impact the ABCA4 protein structure and reduce the retinal-activated ATPase activity, leading to abnormal all-trans retinal accumulation in photoreceptor outer segments and in retinal pigment epithelium cells. The present study broadens the mutational spectrum of the ABCA4 responsible for STGD1. A combination of whole exome sequencing and Sanger sequencing is likely to be a time-saving and cost-efficient approach to screen pathogenic variants in genetic disorders caused by sizable genes, as well as avoiding misdiagnosis. These results perhaps refine genetic counseling and ABCA4-targetted treatments for families affected by STGD1.