Targeted Next Generation Sequencing reveals previously unidentified TSC1 and TSC2 mutations

Mark Nellist, Rutger WW Brouwer, Christel EM Kockx, Monique van Veghel-Plandsoen, Caroline Withagen-Hermans, Lida Prins-Bakker, Marianne Hoogeveen-Westerveld, Alan Mrsic, Mike MP van den Berg, Anna E Koopmans, Marie-Claire de Wit, Floor E Jansen, Anneke JA Maat-Kievit, Ans van den Ouweland, Dicky Halley, Annelies de Klein, Wilfred FJ van IJcken

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in TSC1 and TSC2. Conventional DNA diagnostic screens identify a TSC1 or TSC2 mutation in 75 - 90% of individuals categorised with definite TSC. The remaining individuals either have a mutation that is undetectable using conventional methods, or possibly a mutation in another as yet unidentified gene. Here we apply a targeted Next Generation Sequencing (NGS) approach to screen the complete TSC1 and TSC2 genomic loci in 7 individuals fulfilling the clinical diagnostic criteria for definite TSC in whom no TSC1 or TSC2 mutations were identified using conventional screening methods. We identified and confirmed pathogenic mutations in 3 individuals. In the remaining individuals we identified variants of uncertain clinical significance. The identified variants included mosaic changes, changes located deep in intronic sequences and changes affecting promoter regions that would not have been identified using exon-only based analyses. Targeted NGS of the TSC1 and TSC2 loci is a suitable method to increase the yield of mutations identified in the TSC patient population.