title: Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude.
abstract: BACKGROUND
  Duplication and deletion of the chromosomal region 16p11.2 cause a broad range of impairments, including intellectual disability, language disorders, and sensory symptoms. However, it is unclear how changes in 16p11.2 dosage affect cortical circuitry during development. The aim of this study was to investigate whether the visual evoked potential (VEP) could be used as a noninvasive quantitative measure of cortical processing in children with 16p11.2 copy number variation.
  
  
  METHODS
  Pattern-reversal VEPs were successfully recorded in 19 deletion carriers, 9 duplication carriers, and 13 typically developing children between the ages of 3 and 14 years. The stimulus was a black and white checkerboard (60') that reversed contrast at 2 Hz. VEP responses were extracted from continuous EEG recorded using a high-density elasticized electrode net.
  
  
  RESULTS
  Quantitative analysis of the VEP waveform revealed that, relative to controls, deletion carriers displayed increased amplitude and duplication carriers displayed diminished amplitude. Latencies of the VEP waveform components were unaffected by 16p11.2 status. P1 amplitude did not correlate with age, IQ, or head circumference.
  
  
  CONCLUSIONS
  The results of this study suggest that recording VEP is a useful method to assay cortical processing in children with 16p11.2 copy number variation. There is a gene dosage-dependent effect on P1 amplitude that merits further investigation. The VEP is directly translatable to animal models, offering a promising way to probe the neurobiological mechanisms underlying cortical dysfunction in this developmental disorder.
authors.affiliation: Division of Developmental Medicine, Laboratories of Cognitive Neuroscience, Boston Children's Hospital, Boston, MA USA ; Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA USA ; Department of Neurobiology, Harvard Medical School, Boston, MA USA.
authors.forename: Jocelyn J
authors.initials: JJ
authors.lastname: LeBlanc
authors.affiliation: Division of Developmental Medicine, Laboratories of Cognitive Neuroscience, Boston Children's Hospital, Boston, MA USA ; Department of Pediatrics, Harvard Medical School, Boston, MA USA.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Nelson
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics*; D056915:DNA Copy Number Variations; D002658:Developmental Disabilities / Q000175:diagnosis / Q000503:physiopathology; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D017353:Gene Deletion; D020440:Gene Duplication; D006801:Humans; D008297:Male; D014793:Visual Cortex / Q000000981:diagnostic imaging
keywords: 16p11.2 copy number variation; Visual cortex; Visual evoked potential