title: Brief Report: whole-exome sequencing revealing somatic NLRP3 mosaicism in a patient with chronic infantile neurologic, cutaneous, articular syndrome.
abstract: OBJECTIVE
  To identify the genetic cause of chronic infantile neurologic, cutaneous, articular syndrome (CINCA syndrome) using whole-exome sequencing in a child who had typical clinical features but who was NLRP3 mutation negative based on conventional Sanger sequencing.
  
  
  METHODS
  We performed whole-exome sequencing on DNA from peripheral blood, using Illumina TruSeq Exome capture and the HiSeq sequencing platform. Exome data were analyzed in the Galaxy Web-based suite. Whole-exome sequencing findings were confirmed by massively parallel sequencing.
  
  
  RESULTS
  Analysis of variants in known autoinflammatory genes led to the identification of the pathogenic p.F556L NLRP3 missense mutation in 17.7% of Illumina reads (25 of 141). No new candidate genes were identified. Massively parallel sequencing of DNA from peripheral blood (performed in duplicate) unequivocally confirmed the presence of this mutation in 14.5% of alleles. Reexamination of the original Sanger chromatograms revealed a small peak at nucleotide position c.1698 corresponding to the mutated allele. This had initially been regarded as background noise, but in retrospect is completely consistent with somatic mosaicism for the p.F556L NLRP3 mutation in this child with CINCA syndrome.
  
  
  CONCLUSIONS
  This is the first description of somatic NLRP3 mosaicism detected using whole-exome sequencing in a "mutation-negative" patient with CINCA syndrome. Our findings suggest that whole-exome sequencing could be an important diagnostic tool for detecting somatic mosaicism, as well as for the discovery of novel causative gene mutations, in patients with clinical features of cryopyrin-associated periodic syndromes who are NLRP3 mutation negative by conventional sequencing. This approach could also be applicable to patients with other autosomal-dominant autoinflammatory diseases characterized by gain-of-function mutations who are mutation negative by conventional Sanger sequencing.
authors.affiliation: University College London, London, UK.
authors.forename: Ebun
authors.initials: E
authors.lastname: Omoyinmi
authors.forename: Sónia
authors.initials: S
authors.lastname: Melo Gomes
authors.forename: Ariane
authors.initials: A
authors.lastname: Standing
authors.forename: Dorota M
authors.initials: DM
authors.lastname: Rowczenio
authors.forename: Despina
authors.initials: D
authors.lastname: Eleftheriou
authors.forename: Nigel
authors.initials: N
authors.lastname: Klein
authors.forename: Juan I
authors.initials: JI
authors.lastname: Aróstegui
authors.forename: Helen J
authors.initials: HJ
authors.lastname: Lachmann
authors.forename: Philip N
authors.initials: PN
authors.lastname: Hawkins
authors.forename: Paul A
authors.initials: PA
authors.lastname: Brogan
mesh_terms: D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D056587:Cryopyrin-Associated Periodic Syndromes / Q000235:genetics*; D059472:Exome; D006801:Humans; D008297:Male; D009030:Mosaicism; D020125:Mutation, Missense / Q000235:genetics; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D017422:Sequence Analysis, DNA
chemical_list: D002352:Carrier Proteins; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human