By Reuters Staff
NEW YORK—Genetic variants associated with left-handedness influence brain connectivity and might be related to the pathogenesis of such neuropsychiatric diseases as Parkinson's disease and schizophrenia, researchers from U.K. report.
Left-handedness has an estimated heritability of 25% and has been shown to be associated with several neurodevelopmental disorders, but its genetic basis and neuroanatomical patterns are poorly characterized.
Dr. Dominic Furniss and colleagues of the University of Oxford used data from the U.K. Biobank to examine handedness-related brain imaging patterns, genotypes and phenotypes. Based on findings from 721 left-handers and 6,685 right-handers, left-handers had stronger functional connectivity between right and left language networks and weaker connectivity between the right homologous language network and the default-mode network and salience network.
The genome-wide association study (GWAS) identified four significant loci, three of which involved brain development and patterning genes.
The top single-nucleotide polymorphism (SNP) associated with left-handedness, rs199512, was associated not only with structural connectivity between language areas, but also with several neuropsychiatric phenotypes.
In particular, this SNP was associated with an increased likelihood of neuroticism and mood swings and a decreased likelihood of a maternal history of Parkinson's disease, the researchers report in Brain, online September 5.
Collectively, these SNPs were also significantly associated with an increased likelihood of schizophrenia and a trend-level association with anorexia nervosa and bipolar disorder.
"We suggest that these genetic variants contribute to neurodevelopmental lateralization of brain organization, which in turn influences both the handedness phenotype and the predisposition to develop certain neurological and psychiatric diseases," the researchers conclude.
Dr. Furniss did not respond to a request for comments.
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