The Mutant Gene Causing Canine Early Retinal Degeneration Identifies a Novel Pathway Critical for Photoreceptor Development

Abstract

Purpose: : To evaluate genes within the erd interval as positional candidate genes.

Methods: : DNA and RNA were extracted from normal and affected blood and retina, respectively, using standard protocols. cDNA was prepared using oligo dT. Seven genes were chosen for the initial evaluation. Primers were design to amplify coding sequences and/or genomic fragments within genes for standardized amplification conditions. PCR products were sequenced using the Applied Biosystems Automated 3730 DNA analyzer, and analyzed using Sequencher 4.2.2 software.

Results: : Exons in the interval were sequenced without any significant differences detected. One gene, serine/threonine kinase 38-like protein (STK38L) had a SINE element insertion in erd -affected dogs that causes exon 4 to be skipped during transcription. This predicts the removal of 41 amino acids from the protein translation and elimination of critical conserved functional domains. A zebrafish morpholino based knockout yielded an eye phenotype that ranged from reduced eye size to almost headless fish. Rescue of the MO with wt product to confirm MO specificity is proceeding. One RP patient was found to harbor a non-synonymous change in a highly conserved codon in exon 4.

Keywords: retinal degenerations: hereditary • genetics • gene mapping