The genetic relationship between handedness and neurodevelopmental disorders

Highlights • Genes controlling left/right (LR) body asymmetry also influence handedness. • Some genes associated with handedness or dyslexia are expressed in cilia. • Cilia defects lead to both LR body asymmetry and brain midline phenotypes. • Cilia may play a role in brain midline development, handedness, and dyslexia.
Handedness and brain asymmetry have been linked to neurodevelopmental disorders such as dyslexia and schizophrenia. The genetic nature of this correlation is not understood. Recent discoveries have shown handedness is determined in part by the biological pathways that establish left/right (LR) body asymmetry during development. Cilia play a key role in this process, and candidate genes for dyslexia have also been recently shown to be involved in cilia formation. Defective cilia result not only in LR body asymmetry phenotypes but also brain midline phenotypes such as an absent corpus callosum. These findings suggest that the mechanisms for establishing LR asymmetry in the body are reused for brain midline development, which in turn influences traits such as handedness and reading ability.