Building the brain mosaic: an expanded view.

Brain mosaicism has diverse origins, from early embryogenesis to neurogenesis and in the mature brain. Prezygotic chromosomal abnormalities can be postzygotically corrected, thus leading to tissue-restricted mosaicism. Complex clonal dynamics during embryogenesis determines lineage allocation. Postmitotic neurons continue to accumulate somatic genetic variation. The complexity of the brain is closely tied to its nature as a genetic mosaic, wherein each cell is distinguished by a unique constellation of somatic variants that contribute to functional and phenotypic diversity. Postzygotic variation arising during neurogenesis is recognized as a key contributor to brain mosaicism; however, recent advances have broadened our understanding to include sources of neural genomic diversity that develop throughout the entire lifespan, from embryogenesis through aging. Moving beyond the traditional confines of neurodevelopment, in this review, we delve into the complex mechanisms that enable various origins of brain mosaicism. [ABSTRACT FROM AUTHOR]