# Brain lateralization for perceiving direction of motion is reversed in Williams syndrome and related to BUD23

## TL;DR

This study finds that Williams syndrome causes reversed brain lateralization for motion perception, linked to the BUD23 gene.

## Contribution

The study identifies BUD23 as a gene related to reversed brain lateralization in Williams syndrome.

## Key findings

- Williams syndrome shows reversed lateralization for motion perception from right to left hemisphere.
- BUD23 transcript levels correlate with reversed lateralization and mental rotation performance.
- BUD23 is implicated in human brain laterality and cognitive impairments in genetic disorders.

## Abstract

Lateralized nervous system function is phylogenetically old but fundamentally important for human brain function. Although altered in developmental and psychiatric disorders, we know little about its genetics. To understand the genetic origins of hemispheric specialization, we investigated laterality in a genetic disorder, Williams Syndrome (WS), caused by ~ 27 deleted genes on 7q11.2. Using a multidisciplinary approach combining individuals’ molecular genetic, electrophysiological, and behavioral data, we identify reversed lateralization, from right to left hemisphere for perceiving direction of motion in WS and show hemispheric strengths are inversely correlated. Moreover, we correlate decreased transcript levels of the deleted gene BUD23, with strength of the reversed lateralization and with decreased performance in mental rotation, another right hemisphere lateralized function. The results implicate dosed BUD23, an 18S ribosomal RNA methyltransferase, in human brain laterality, support an evolutionary origin and provide altered lateralization as a novel mechanism for impaired cognition in genetic and behavioral disorders.

The online version contains supplementary material available at 10.1038/s41598-025-94742-3.