Expanding the Genotype-Phenotype Correlations and Mutational Spectrum in Inherited Retinal Diseases: Novel and Recurrent Mutations

Ibrahim Sahin; Haktan B Erdem; Taha Bahsi; Hanife Saat

doi:10.7759/cureus.53742

Expanding the Genotype-Phenotype Correlations and Mutational Spectrum in Inherited Retinal Diseases: Novel and Recurrent Mutations

Cureus. 2024 Feb 6;16(2):e53742. doi: 10.7759/cureus.53742. eCollection 2024 Feb.

Authors

Ibrahim Sahin^{1

2}, Haktan B Erdem³, Taha Bahsi³, Hanife Saat³

Affiliations

¹ Department of Molecular Medicine, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, BHR.
² Department of Medical Genetics, University of Health Sciences, Dışkapı Yıldırım Beyazıt Training and Research Hospital, Ankara, TUR.
³ Department of Medical Genetics, Ankara Etlik City Hospital, Ankara, TUR.

Abstract

Background Inherited retinal diseases (IRD) represent a prominent etiology of visual impairment on a global scale. The lack of a clear definition of the etiology and genotypic spectrum of IRD is attributed to the significant genetic variability seen. Additionally, there is a scarcity of available data about the correlations between genotypes and phenotypes in this context. This study aimed to clarify the range of mutations and the associations between genotypes and phenotypes in IRD. Methods This cohort consists of 223 patients who have been diagnosed with a range of retinal illnesses, such as retinitis pigmentosa (RP), Stargardt (STGD)/STGD-like disease, Usher syndrome, and Leber congenital amaurosis (LCA). The validation of each mutation and its pathogenicity was conducted by bioinformatics analysis, Sanger sequencing-based co-segregation testing, and computational assessment. The link between genotype and phenotype was analyzed in all patients who possessed mutations as described in the recommendations established by the American College of Medical Genetics. Results A total of 223 cases, comprising Turkish and Syrian families, were examined, revealing the presence of 175 distinct mutations in the IRD gene. Among these mutations, 58 were identified as unique, indicating that they had not been previously reported. A total of 119 mutations were identified to be likely pathogenic, while 104 mutations were classified as pathogenic. The study identified patterns of heredity, namely autosomal recessive, dominant, and X-linked inheritance. Conclusions The findings of this study broaden the clinical and molecular aspects of IRD and further enhance our understanding of its complex nature. The discovery of previously unknown relationships between genetic variations and observable traits, as well as the wide range of genetic variants associated with IRD, significantly contributes to our existing understanding of the diverse phenotypic and genotypic characteristics of IRD. This new information will prove invaluable in facilitating accurate clinical diagnoses as well as personalized therapeutic interventions for individuals affected by IRD.

Keywords: leber congenital amaurosis; ngs; retina; retinitis pigmentosa; retinopathy; stargardt syndrome; usher syndrome.