Sex chromosome trisomies are not associated with atypical lateralisation for language

Abstract

AimIndividuals with a sex chromosome trisomy (SCT) have disproportionate problems with language compared to nonverbal skills. This may result from disruption to the typical left hemisphere bias for language processing. We tested the hypothesis that SCTs would be associated with reduced left lateralisation for language.\n\nMethodIn a cross-sectional design, language laterality was measured during an animation description task using functional transcranial Doppler ultrasonography (fTCD). Data were available for 75 children with an SCT (26 47,XXX girls, 25 47,XXY boys, and 24 47,XYY boys; mean age was 11;4 years, SD = 3;10 years), and 132 comparison children with typical karyotypes (69 boys; mean age was 9;1 years, SD = 1;7 years).\n\nResultsLateralisation for language did not differ between the SCT and comparison groups, either in mean laterality index or relative frequency of each laterality category (left, bilateral and right). There were no differences when splitting the SCT group by trisomy. Handedness also showed no group effects.\n\nInterpretationOur data provide no evidence for disrupted lateralisation for language in SCTs. The brain basis of the cognitive phenotype in SCTs is unlikely to be a failure of the left hemisphere to specialise for language, as previously suggested.\n\nWhat this paper addsO_LIChildren with a sex chromosome trisomy (SCT) have typically lateralised language.\nC_LIO_LIThis disconfirms theories linking language problems to hemispheric specialization in SCTs\nC_LI