title: Heritability and reliability of P300, P50 and duration mismatch negativity.
abstract: BACKGROUND
  Event-related potentials (ERPs) have been suggested as possible endophenotypes of schizophrenia. We investigated the test-retest reliabilities and heritabilities of three ERP components in healthy monozygotic and dizygotic twin pairs.
  
  
  METHODS
  ERP components (P300, P50 and MMN) were recorded using a 19-channel electroencephalogram (EEG) in 40 healthy monozygotic twin pairs, 19 of them on two separate occasions, and 30 dizygotic twin pairs. Zygosity was determined using DNA genotyping.
  
  
  RESULTS
  High reliabilities were found for the P300 amplitude and its latency, MMN amplitude, and P50 suppression ratio components. ICC=0.86 and 0.88 for the P300 amplitude and P300 latency respectively. Reliability of MMN peak amplitude and mean amplitude were 0.67 and 0.66 respectively. P50 T/C ratio reliability was 0.66. Model fitting analyses indicated a substantial heritability or familial component of variance for these ERP measures. Heritability estimates were 63 and 68% for MMN peak amplitude and mean amplitude respectively. For P50 T/C ratio, 68% heritability was estimated. P300 amplitude heritability was estimated at 69%, and while a significant familiality effect was found for P300 latency there was insufficient power to distinguish between shared environment and genetic factors.
  
  
  CONCLUSIONS
  The high reliability and heritability of the P300 amplitude, MMN amplitude, and P50 suppression ratio components supports their use as candidate endophenotypes for psychiatric research.
authors.affiliation: Social, Genetic Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College London, PO80, De Crespigny Park, London, SE5 8AF, UK. spgemhh@iop.kcl.ac.uk
authors.forename: Mei Hua
authors.initials: MH
authors.lastname: Hall
authors.forename: Katja
authors.initials: K
authors.lastname: Schulze
authors.forename: Frühling
authors.initials: F
authors.lastname: Rijsdijk
authors.forename: Marco
authors.initials: M
authors.lastname: Picchioni
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ettinger
authors.forename: Elvira
authors.initials: E
authors.lastname: Bramon
authors.forename: Robert
authors.initials: R
authors.lastname: Freedman
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.forename: Pak
authors.initials: P
authors.lastname: Sham
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000235:genetics*; D005133:Eye Movements / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008131:London; D008297:Male; D008875:Middle Aged; D008957:Models, Genetic; D012042:Registries; D015203:Reproducibility of Results; D012559:Schizophrenia / Q000235:genetics; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic