Targeted next-generation sequencing identifies ABCA4 mutations in Chinese families with childhood-onset and adult-onset Stargardt disease

Abstract

Background: Stargardt disease (STGD) is the most common form of juvenile macular dystrophy associated with progressive central vision loss, and is agenetically and clinically heterogeneous disease. Molecular diagnosis is of great significance in aiding the clinical diagnosis, helping to determine the phenotypic severity and visual prognosis. In this study, we determined the clinical and genetic features of seven childhood-onset and three adult-onset Chinese STGD families. We performed capture next generation sequencing (NGS) of the probands and searched for potentially disease-causing genetic variants in previously identified retinal or macular dystrophy genes.  Methods: In all, 10unrelated Chinese families were enrolled. Panel based NGS was performed to identify potentially disease-causing genetic variants in previously identified retinal or macular dystrophy genes, including the five known STGD genes (ABCA4, PROM1, PRPH2, VMD2 and ELOVL4). Variant analysis, Sanger validation, and segregation tests were utilized to validate the disease-causing mutations inthese families. Results: Using systematic data analysis with an established bioinformatics pipeline and segregation analysis, 17 pathogenic mutations in ABCA4 were identified in the ten STGD families. Four of these mutations were novel: c.371delG, c.681T > G, c.5509C > T and EX37del. Childhood-onset STGD was associated with severe visual loss, generalized retinal dysfunction and was due to more severe variants in ABCA4 than those found in adult-onset disease. Conclusions: We expand the existing spectrum of STGD and reveal the genotype-phenotype relationships of the ABCA4 mutations in Chinese patients. Childhood-onset STGD lies at the severe end of the spectrum of ABCA4-associated retinal phenotypes.

Structural and Pathogenic Impacts of ABCA4 Variants in Retinal Degenerations—An In-Silico Study

“…In the ClinVar database, there are currently 93 missense ABCA4 variants falling within these regions. A limited number of these variants have been computationally analyzed using classical informatics-based tools [ 59 , 60 , 61 ] or are reported as part of the submission to the databases, such as ClinVar. Nearly 90% of these variants are VUS ( (accessed on 31 March 2023)).…”