Next-generation variant exon screening: Moving forward in routine genetic disease investigations

Abstract

Purpose: Patients with genetic diseases often seek testing to reach a firm diagnosis. Based on clinical phenotypes, exome sequencing for small-nucleotide variations or array-based methods for copy-number variations (CNVs) are commonly offered to identify the underlying causative genetic variants. In this study, we investigated whether data from a standard ES test could be used to additionally identify pathogenic CNVs and increase diagnostic yield. Methods: Prospectively, 134 patients presenting with a skin condition suspected of being genetic in origin were offered the next-generation variant exon screening (ngVES) test. Sequencing data were analyzed for both single-nucleotide variants and CNVs using established algorithms. Results: The positive detection rate for skin diseases using ngVES was 66% (88/134) with the most common diagnoses being neurofibromatosis type1 (n = 48) and tuberous sclerosis type2 (n = 12). The diagnostic increased yield from 58% to 66% was the result of additional detection of pathogenic CNVs. Each of the 9 CNVs were verified by independent genetic tests. Conclusion: The advances in the ngVES bioinformatics pipeline are proofs of concept, which improved identification of genetic variants associated with skin disease. Simultaneous single-nucleotide variants/INDEL and CNV detection by this approach demonstrates ngVES potential as a first-tier screen for any suspected genetic disease.

Keywords

• Copy-number variants
• Nucleotide variants
• Skin diseases
• Variant exon screening