Identification of a novel non-stop mutation in PDE6C gene in an Iranian family with Con-Rod Dystrophy

Cone-rod dystrophy (CORD) is one of the most common genetic eye disorders. Recent genetic studies have demonstrated that it is a genetically heterogeneous disease among patients. Molecular genetic analysis of the 22 genes was performed in a family with Cone-rod dystrophy. Bioinformatics was applied for Next Generation Sequencing, and the variants were confirmed by Sanger sequencing. In this study, the nonstop mutation in the PDE6C gene (a normal stop codon is 859th codon of PDE6C located in exon 22 TAA (Stop) --> CAA (Gln) = Stop859Q) leads to a termination-site change and run-on into the 3' untranslated region (UTR) that predicts an extended protein which was found in the family. This mutation has not been described in patients with the CORD phenotype. Also, this is the first study indicating that a nonstop mutation in the homozygous state in PDE6C is responsible for the congenital recessive CORD phenotype.