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.

A nonstop mutation in the factor (F)X gene of a severely haemorrhagic patient with complete absence of coagulation FX

SummaryWe identified a previously unknown mutation by sequencing the factor (F)X gene in a severely haemorrhagic 14-year-old maleAfrican-American individual with undetectable plasma FX-activity and -antigen levels. This mutation, called F10-Augusta, was homozygote and is a combination of an 8bp insertion in flanking 3’-genomic-DNA and a 5bp terminal exon-8 deletion involving codons 437 and 438. Sequencing of RT-PCR and 3’-RACE products showed that the F10-Augusta transcript is normally processed but lacks an in-frame stop codon. An allele specific 3’-RACE-based RFLP assay demonstrated that the steady-state concentration of the mutant transcript was markedly lower than that of the wild-type message in total-RNA samples from the patient’s unaffected heterozygous parents. The recently discovered nonstop decay mechanism, a component pathway of the mRNA surveillance system, is a possible explanation for the reduced concentration of the mutant FX transcript. This is the first report implying such a mechanism in the pathogenesis of inherited bleeding disorders.