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Jean-Yves Deslandes, Mathilde Giraud, Bertrand Isidor, Patricia Talarmain, Ingrid Maury, Severine Marconi, Guylene Le Meur, Michel Weber, Isabelle Meunier, Christian Hamel, Stéphane Bezieau; Prevalence of mutations in PDE6B gene in autosomal recessive retinitis pigmentosa in the aim of gene therapy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):38. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the prevalence of PDE6B mutations in autosomal recessive retinitis pigmentosa in order to set a specific PDE6B gene therapy. This gene that encodes the beta subunit of PDE (phosphodiesterase) a peripheral membrane heterotrimeric enzyme could be involved in about 4% of autosomal recessive retinitis pigmentosa (arRP), and rarely in autosomal dominant congenital stationnary night blindness.
421 unrelated patients (index cases) with arRP examined in two out clinics specialised in inherited dystrophies were included. Patients had night blindness, visual or field anomalies, peripheral bone spicules, hyperfluorescent perifoveal ring or hypoautofluorescent spots on autofluorescent frames, ellipsoid zone alterations on SD-OCT and reduced rod responses on ISCEV electroretinogram. Genetic analyses were performed using a PDE6B custom HaloPlex (AgilentR) capture panel designed with SureDesign software to screen all coding sequence and splice junctions with 98.87% of coverage. HaloPlexXT Target Enrichment System Kit for Illumina sequencing was used for capture and products sequence on MiSeq using the MiseqXT protocol (IlluminaR). Data were analysed on two bioinformatic pipelines using human PDE6B gene reference NM_000283.3. A first pipeline involved alignment, coverage analysis and variant calling with the SeqNext module of the SeqPilot software v4.1.2). Bases with a quality score <20 which were filtered-out. A second pipeline analysing each Illumina MiSeq run was developed. Variations were considered as pathogenic if described in literature and predicted to be pathogenic by in silico prediction tools dbSNP, SIFT, Polyphen and ClinVar. Identified mutations were confirmed by Sanger sequencing and familial segregation was studied.
Six out of 421 patients had either heterozygous (4 patients) or homozygous (4 patients) pathogenic mutations in PDE6B gene that explains the phenotype. In other 4 patients, only one mutation was identified. There were 10 exonic variants (8 missense, 1 nonsense, and 1 deletion/insertion variations) and 2 splice-sites variations. All mutations were found in highly conserved regions showing a putative important function for the residues.
Mutations in PDE6B are rare accounting for 1.4% (5/421) of arRP in this cohort. In four additional cases of RP, we cannot conclude about the role of PDE6B as only one exonic mutation was identified.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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