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N. Smaoui, N. Nwokekeh, L. Chang, R.C. Caruso, B.P. Brooks, P.A. Sieving, J.F. Hejtmancik; NEI DNA Diagnostic Laboratory, Overview of the First Three Years . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4602. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The National Eye Institute has established a DNA Diagnostic laboratory in order to provide CLIA certified DNA testing for various ocular genetic diseases and to facilitate the identification of genotype–phenotype correlations, and to help delineate inherited ocular diseases.
Patients were referred for molecular DNA diagnosis from within and without the NEI, after being diagnosed by clinical ophthalmic examination. Genomic DNA was extracted from peripheral blood and used to amplify the coding sequence of several ocular genes in a polymerase chain reaction with primers located in adjacent introns. Exons, including coding sequence and intron–exon boundaries, were sequenced using ABI BigDye Terminator V3.1 with an ABI3100 Genetic Analyzer.
In 2003, the first year of this project, tests were performed on a total of 20 patients, analyzing one of two genes, CHM and RS1. In 2004 two more genes, NYX and RHO were added and a total of 101 patients were diagnosed. In 2005 and additional 3 genes, PAX6, CYP4V2 and RPGR including ORF15 were added to our diagnostic repertoire with 146 tests performed. Mutations were identified in XLRS1 in 67 families (90% of those analyzed), in CHM in 11 families (65% of those analyzed), in RHO in 9 families (28% of those analyzed), in CYP4V2 in 2 families (65% of those analyzed), in PAX6 in 3 families (50% of those analyzed), and finally in RPGR in 8 families (45% of those analyzed). DNA testing results were interpreted and risks assessed by discussion between laboratory staff and the clinical geneticist.
We have identified deleterious mutations in 50% of the families referred for analysis of ocular genetic diseases. A total of 39 mutations were novel. In some cases, the clinical presentation was atypical and the clinical diagnosis was adjusted or confirmed by the molecular analysis. In addition, identification of the molecular defect in inherited ophthalmic diseases will allow a better targeting of patients for future clinical trials and contribute to the nosology of inherited ophthalmic diseases.
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