title: Evidence for the late MMN as a neurophysiological endophenotype for dyslexia.
abstract: Dyslexia affects 5-10% of school-aged children and is therefore one of the most common learning disorders. Research on auditory event related potentials (AERP), particularly the mismatch negativity (MMN) component, has revealed anomalies in individuals with dyslexia to speech stimuli. Furthermore, candidate genes for this disorder were found through molecular genetic studies. A current challenge for dyslexia research is to understand the interaction between molecular genetics and brain function, and to promote the identification of relevant endophenotypes for dyslexia. The present study examines MMN, a neurophysiological correlate of speech perception, and its potential as an endophenotype for dyslexia in three groups of children. The first group of children was clinically diagnosed with dyslexia, whereas the second group of children was comprised of their siblings who had average reading and spelling skills and were therefore "unaffected" despite having a genetic risk for dyslexia. The third group consisted of control children who were not related to the other groups and were also unaffected. In total, 225 children were included in the study. All children showed clear MMN activity to/da/-/ba/contrasts that could be separated into three distinct MMN components. Whilst the first two MMN components did not differentiate the groups, the late MMN component (300-700 ms) revealed significant group differences. The mean area of the late MMN was attenuated in both the dyslexic children and their unaffected siblings in comparison to the control children. This finding is indicative of analogous alterations of neurophysiological processes in children with dyslexia and those with a genetic risk for dyslexia, without a manifestation of the disorder. The present results therefore further suggest that the late MMN might be a potential endophenotype for dyslexia.
authors.affiliation: Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Munich, Munich, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Neuhoff
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bruder
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bartling
authors.forename: Andreas
authors.initials: A
authors.lastname: Warnke
authors.forename: Helmut
authors.initials: H
authors.lastname: Remschmidt
authors.forename: Bertram
authors.initials: B
authors.lastname: Müller-Myhsok
authors.forename: Gerd
authors.initials: G
authors.lastname: Schulte-Körne
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D004410:Dyslexia / Q000235:genetics / Q000503:physiopathology* / Q000523:psychology; D004569:Electroencephalography; D058068:Endophenotypes; D005072:Evoked Potentials, Auditory / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D009424:Nervous System Physiological Phenomena; D035781:Siblings / Q000523:psychology