July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Careful clinical-functional phenotyping combined with systematic, broad NGS Panel-based genotyping identify numerous novel disease-causing mutations and deletions in inherited retinal dystrophy (IRD) patients
Author Affiliations & Notes
  • Alessandro Iannaccone
    Duke Eye Center, Duke University Medical Center, Durham, North Carolina, United States
  • Jay Berdia
    Duke Eye Center, Duke University Medical Center, Durham, North Carolina, United States
  • Wajiha Kheir
    Duke Eye Center, Duke University Medical Center, Durham, North Carolina, United States
  • Lindsay Mighion
    EGL Genetics, Tucker, Georgia, United States
  • Nicholas Wang
    Molecular Vision Laboratory, Hillsboro, Oregon, United States
  • Cristina DaSilva
    EGL Genetics, Tucker, Georgia, United States
  • Jie Duan
    Molecular Vision Laboratory, Hillsboro, Oregon, United States
  • John J. Alexander
    Dept. Human Genetics, Emory University, Atlanta, Georgia, United States
    EGL Genetics, Tucker, Georgia, United States
  • John (P-W) Chiang
    Molecular Vision Laboratory, Hillsboro, Oregon, United States
  • Footnotes
    Commercial Relationships   Alessandro Iannaccone, None; Jay Berdia, None; Wajiha Kheir, None; Lindsay Mighion, EGL Genetics (E); Nicholas Wang, Molecular Vision Lab (E); Cristina DaSilva, EGL Genetics (E); Jie Duan, Molecular Vision Lab (E); John Alexander, EGL Genetics (E); John (P-W) Chiang, Molecular Vision Laboratory (E)
  • Footnotes
    Support  Research to Prevent Blindness, Inc. New York, NY (Unrestricted grant to Duke Eye Center)
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 5410. doi:
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      Alessandro Iannaccone, Jay Berdia, Wajiha Kheir, Lindsay Mighion, Nicholas Wang, Cristina DaSilva, Jie Duan, John J. Alexander, John (P-W) Chiang; Careful clinical-functional phenotyping combined with systematic, broad NGS Panel-based genotyping identify numerous novel disease-causing mutations and deletions in inherited retinal dystrophy (IRD) patients. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5410.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : There is widespread consensus that genotyping IRD patients is essential, but there is still much debate as to what the best approach to IRD genotyping should be. Here we report our experience with the characterization of IRD patients based on the judicious combination of careful clinical-functional phenotyping with systematic genotyping.

Methods : We investigated a consecutive case series of >150 molecularly uncharacterized IRD patients (age: 2-75 yo). In addition to pedigree collection, phenotyping included in-depth history collection with a standardized vision and review-of-systems questionnaire, complete eye exams, imaging studies, and various types of visual fields and electroretinograms. Targeted/focused genotyping was possible only in select cases. In the vast majority of patients, NGS-based panel testing was needed, at baseline or as a reflex strategy. Negative or ambiguous results were followed by deletion/duplication (del/dup) microarray testing. Parental samples were included for phase assessment whenever possible.

Results : While broad panels often revealed many genetic variants of uncertain significance (VOUS), careful reconciliation of genotypic results with phenotypic data led to the conclusive molecular characterization of >85% of the cases and to the identification of numerous novel disease-causing mutations and deletions, especially in minority subjects. In a number of cases, del/dup testing was essential, and reflexing to it relied heavily on phenotypic input. Some atypical phenotypes were clarified only after genotyping. The detail of these novel mutations and deletions will be presented, and phenotypes will be illustrated.

Conclusions : Targeted testing is possible (and advisable) in selected cases, but most often it is simply not possible and can prove cost-escalating. In turn, a shot-gun genotyping approach without careful phenotyping is dangerous since it can lead to VOUS overload, confusion, incorrect conclusions, and at times unnecessarily high costs. In our hands, a judicious use of meticulous, expert clinical-functional phenotyping combined with systematic, broad NGS Panel-based genotyping was extremely effective at the diagnostic end, reduced costs and saved time. Clinician-laboratory two-way interactions and discussions augment the efficacy of this approach.

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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