title: Genetics of callous-unemotional behavior in children.
abstract: Callous-unemotional behavior (CU) is currently under consideration as a subtyping index for conduct disorder diagnosis. Twin studies routinely estimate the heritability of CU as greater than 50%. It is now possible to estimate genetic influence using DNA alone from samples of unrelated individuals, not relying on the assumptions of the twin method. Here we use this new DNA method (implemented in a software package called Genome-wide Complex Trait Analysis, GCTA) for the first time to estimate genetic influence on CU. We also report the first genome-wide association (GWA) study of CU as a quantitative trait. We compare these DNA results to those from twin analyses using the same measure and the same community sample of 2,930 children rated by their teachers at ages 7, 9 and 12. GCTA estimates of heritability were near zero, even though twin analysis of CU in this sample confirmed the high heritability of CU reported in the literature, and even though GCTA estimates of heritability were substantial for cognitive and anthropological traits in this sample. No significant associations were found in GWA analysis, which, like GCTA, only detects additive effects of common DNA variants. The phrase 'missing heritability' was coined to refer to the gap between variance associated with DNA variants identified in GWA studies versus twin study heritability. However, GCTA heritability, not twin study heritability, is the ceiling for GWA studies because both GCTA and GWA are limited to the overall additive effects of common DNA variants, whereas twin studies are not. This GCTA ceiling is very low for CU in our study, despite its high twin study heritability estimate. The gap between GCTA and twin study heritabilities will make it challenging to identify genes responsible for the heritability of CU.
authors.affiliation: King's College London, Medical Research Council Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, De Crespigny Park, London, United Kingdom. e.viding@ucl.ac.uk
authors.forename: Essi
authors.initials: E
authors.lastname: Viding
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Price
authors.forename: Sara R
authors.initials: SR
authors.lastname: Jaffee
authors.forename: Maciej
authors.initials: M
authors.lastname: Trzaskowski
authors.forename: Oliver S P
authors.initials: OS
authors.lastname: Davis
authors.forename: Emma L
authors.initials: EL
authors.lastname: Meaburn
authors.forename: Claire M A
authors.initials: CM
authors.lastname: Haworth
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
mesh_terms: D002648:Child; D019955:Conduct Disorder / Q000235:genetics*; D005260:Female; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008957:Models, Genetic; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable; D012984:Software