title: Validation of next-generation sequencing technologies in genetic diagnosis of dementia.
abstract: Identification of a specific genetic cause of early onset dementia (EOD) is important but can be difficult because of pleiotropy, locus heterogeneity and accessibility of gene tests. Here we assess the use of next generation sequencing (NGS) technologies as a quick, accurate and cost effective method to determine genetic diagnosis in EOD. We developed gene panel based technologies to assess 16 genes known to harbour mutations causal of dementia and combined these with PCR based assessments of the C9orf72 hexanucleotide repeat expansion and the octapeptide repeat region of PRNP. In a blinded study of 95 samples we show very high sensitivity and specificity are achievable using either Ion Torrent or MiSeq sequencing platforms. Modifications to the gene panel permit accurate detection of structural variation in APP. In 2/10 samples which had been selected because they possess a variant of uncertain significance the new technology discovered a causal mutation in genes not previously sequenced. A large proportion (23/85) of samples showed genetic variants of uncertain significance in addition to known mutations. The MRC Dementia Gene Panel and similar technologies are likely to be transformational in EOD diagnosis with a significant impact on the proportion of patients in whom a genetic cause is identified.
authors.affiliation: MRC Prion Unit, Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK.
authors.forename: John
authors.initials: J
authors.lastname: Beck
authors.forename: Alan
authors.initials: A
authors.lastname: Pittman
authors.forename: Gary
authors.initials: G
authors.lastname: Adamson
authors.forename: Tracy
authors.initials: T
authors.lastname: Campbell
authors.forename: Joanna
authors.initials: J
authors.lastname: Kenny
authors.forename: Henry
authors.initials: H
authors.lastname: Houlden
authors.forename: Jon D
authors.initials: JD
authors.lastname: Rohrer
authors.forename: Rohan
authors.initials: R
authors.lastname: de Silva
authors.forename: Maryam
authors.initials: M
authors.lastname: Shoai
authors.forename: James
authors.initials: J
authors.lastname: Uphill
authors.forename: Mark
authors.initials: M
authors.lastname: Poulter
authors.forename: John
authors.initials: J
authors.lastname: Hardy
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Mummery
authors.forename: Jason D
authors.initials: JD
authors.lastname: Warren
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Schott
authors.forename: Nick C
authors.initials: NC
authors.lastname: Fox
authors.forename: Martin N
authors.initials: MN
authors.lastname: Rossor
authors.forename: John
authors.initials: J
authors.lastname: Collinge
authors.forename: Simon
authors.initials: S
authors.lastname: Mead
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000073885:C9orf72 Protein; D042622:DNA Repeat Expansion; D003704:Dementia / Q000175:diagnosis* / Q000235:genetics*; D014644:Genetic Variation; D006801:Humans; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D000072002:Prion Proteins; D011328:Prions / Q000235:genetics; D011506:Proteins / Q000235:genetics; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: C545487:APP protein, human; D016564:Amyloid beta-Protein Precursor; D000073885:C9orf72 Protein; C568651:C9orf72 protein, human; C512656:PRNP protein, human; D000072002:Prion Proteins; D011328:Prions; D011506:Proteins
keywords: Dementia; Diagnosis; Genetic; Ion torrent; MiSeq; NGS; Neurogenetics; Next-generation sequencing; Sequencing