Abstract
Purpose :
Retinoschisis is caused by mutations in the gene RS1 which codes for the retinoschisin protein. Causative mutations can be found in approximately 100% of cases. We evaluate a sample that was found to be negative for mutations in the RS1 coding regions by screening for other candidate variants in the intronic regions.
Methods :
Genomic DNA is extracted from peripheral blood and used to amplify the coding sequence of the RS1 gene in a polymerase chain reaction (PCR). PCR amplification is performed with Big Dye Direct sequencing kit. Sequencing amplification is performed in both directions with the ABI Big Dye Terminator v3.1 kit. Sequencing products are analyzed with an ABI Prism 3130xl Genetic Analyzer. Sequence data are compared with references using Mutation Surveyor 4.0.9 software (www.softgenetics.com). Variant analysis is performed using Alamut (www.interactive-biosoftware.com).
Results :
We found an intronic variant 34 bases upstream of exon 2 in this retinoschisis patient. This change, NM_000330.3:c.53-34A>G (g.18675819T>C), could lead to the formation of a new acceptor site and 11 spurious amino acids to the protein. Mother and maternal cousin were also Sanger sequenced and found to be heterozygous and hemizygous for this change respectively, demonstrating co-segregation of the intron variant with the disease in this family.
Conclusions :
Our results suggest that this intronic change could be damaging. However, the correlation is not strong enough. There is no evidence demonstrating the existence of the predicted alternative spliced transcript in the patient yet. Further study of this variant is needed in order to establish the pathogenicity.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.