Effects of catechol-O-methyltransferase on normal variation in the cognitive function of children.
OBJECTIVE
Genetic variants that contribute to the risk of psychiatric disorders may also affect normal variation in psychological function. Indeed, the behavioral effects of many genetic variants may be better understood as process-specific rather than disease-specific. A functional valine-to-methionine (Val(158)Met) polymorphism in the catechol-O-methyltransferase (COMT) gene has been associated with cognitive function and brain metabolic activity accompanying such tasks. Not all studies are consistent, and less is known about the effect of this polymorphism during development. The authors tested the hypothesis that a more informative COMT haplotype predicts normal cognitive development in a large population-based cohort of children enrolled in the Avon Longitudinal Study of Parents and Children.


METHODS
Effects on verbal and performance IQ as well as verbal inhibition were assessed at age 8, and effects on working memory were assessed at age 10. From the five COMT single nucleotide polymorphisms (SNPs) genotyped, the effect of a functional three-SNP haplotype consisting of Val(158)Met and two synonymous SNPs (rs6269 and rs4818), which together exert a major influence on the level of COMT expression and enzyme activity, was evaluated.


RESULTS
This three-SNP haplotype predicted both verbal inhibition and working memory, and there was a genotype-by-sex interaction on verbal IQ. The effect of COMT genotype (diplotype) on cognition was curvilinear, which is consistent with the "inverted U" model of dopamine effect on frontal cortical efficiency. In addition, the SNP rs2075507 (previously rs2097603) was independently associated with verbal inhibition, while rs165599 showed no main cognitive effects. However, rs165599 showed a genotype-by-sex interaction with working memory.


CONCLUSIONS
Genetic variation at several loci in the COMT gene affects normal cognitive function in children.
Barnett
Jennifer H
JH
Department of Psychiatryand the Centre for Family Research, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK. jhb32@cam.ac.uk
Heron
Jon
J
Goldman
David
D
Jones
Peter B
PB
Xu
Ke
K
D002394:Catechol O-Methyltransferase / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002648:Child; D002657:Child Development / Q000502:physiology*; D002874:Chromosome Mapping; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics / Q000378:metabolism; D003071:Cognition / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation / Q000235:genetics; D005838:Genotype; D006239:Haplotypes / Q000235:genetics; D006801:Humans; D007361:Intelligence Tests; D016014:Linear Models; D015810:Linkage Disequilibrium / Q000235:genetics; D008137:Longitudinal Studies; D008297:Male; D008715:Methionine / Q000235:genetics / Q000378:metabolism; D009483:Neuropsychological Tests; D020641:Polymorphism, Single Nucleotide; D014633:Valine / Q000235:genetics / Q000378:metabolism
D008715:Methionine; D002394:Catechol O-Methyltransferase; D014633:Valine