Titel: Optimized clinical exome design to analyse complex genetic regions covering all inherited eye diseases and retinal dystrophies
ID: P-ClinG-050
Art: Postertalk
Redezeit: 2 min
Session: Poster Session
ClinG 2

Referent: Tobias Eisenberger (Mainz/DE), Valeska Frank (Mainz/DE)

Abstract - Text


Analysis of non-syndromic and syndromic retinal dystrophies requires comprehensive testing approaches due to huge genetic heterogeneity. Limitations of NGS-based testing in difficult-to-target regions due to highly repetitive or homologous nature of the underlying genomic sequence are well known. Therefore, we have developed an optimized design of a clinical exome that targets any gene based on public and licenced mutation/variant databases (HGMD, ClinVar) also including non-coding variants. Sequencing at higher coverage and validating the bioinformatic processing of the data, better performance and sensitivity than observed in out-of-the-shelf WES products could be demonstrated. Moreover, more robust validity is demonstrated for copy-number-variations. Genomic rearrangements and a multitude of different microdeletion syndromes conventially analysed by approaches like array-CGH are also reliably detected by our one-step testing setup.

Our design is optimized and allows the analysis of all genes associated with inherited eye disorders such as retinal dystrophies. Awareness of technical limitations of available testing kits as well as of the presence of the complex nature in critical genes requires in depth knowledge about the underlying genomic regions and disease pathomechanisms. X-linked retinitis pigmentosa (XLRP) is an important cause of blindness in males. The major gene for XLRP is RPGR with most variants located in its ORF15 region. Due to its highly repetitive purine-rich sequence, conventional sequencing of ORF15 is cumbersome and comprehensive next-generation sequencing (NGS) has remained challenging. With an optimized custom design we demonstrate sufficient coverage of the purine-rich sequence region. Performance analysis demonstrates high sensitivity in the detection of variants within ORF15.

We additionally addressed mitochondrial diseases in our custom design and included mtDNA analysis after intensive validation of its technical performance.

In conclusion, our clinical exome approach allows for fast, reliable and comprehensive analysis of all known genes for retinal degeneration, including one of the most prevalent single genetic loci in RP, ORF15 in RPGR, which is a major target for ocular gene therapy.