Increasing the Genetic Diagnosis Yield in Inherited Retinal Dystrophies: Assigning Pathogenicity to Novel Non-canonical Splice Site Variants.

AIMS

We aimed to validate the pathogenicity of genetic variants identified in inherited retinal dystrophy (IRD) patients, which were located in non-canonical splice sites (NCSS).

METHODS

After next generation sequencing (NGS) analysis (target gene panels or whole exome sequencing (WES)), NCSS variants were prioritized according to predictions. and functional tests were used to validate their pathogenicity.

RESULTS

Four novel NCSS variants have been identified. They are located in intron 33 and 34 of (c.4774-9G>A and c.4849-8C>G, respectively), intron 2 of (c.101-3T>G) and intron 3 of (c.884-14G>A). Functional analysis detected different aberrant splicing events, including intron retention, exon skipping and intronic nucleotide addition, whose molecular effect was either the disruption or the elongation of the open reading frame of the corresponding gene.

CONCLUSIONS

Our data increase the genetic diagnostic yield of IRD patients and expand the landscape of pathogenic variants, which will have an impact on the genotype-phenotype correlations and allow patients to opt for the emerging gene and cell therapies.