Michael A. Lodato1,*, Mollie B. Woodworth1,*, Semin Lee2,*, Gilad D. Evrony1, Bhaven K. Mehta1, Amir Karger3, Soohyun Lee2, Thomas W. Chittenden3,4,†, Alissa M. D’Gama1, Xuyu Cai1,‡, Lovelace J. Luquette2, Eunjung Lee2,5, Peter J. Park2,5,§, Christopher A. Walsh1,§
1Division of Genetics and Genomics, Manton Center for Orphan Disease, and Howard Hughes Medical Institute, Boston Children’s Hospital, Boston, MA, USA; Departments of Neurology and Pediatrics, Harvard Medical School, Boston, MA, USA; and Broad Institute of MIT and Harvard, Cambridge, MA, USA.
2Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA.
3Research Computing, Harvard Medical School, Boston, MA, USA.
4Complex Biological Systems Alliance, North Andover, MA, USA.
5Division of Genetics, Brigham and Women’s Hospital, Boston, MA, USA.
† Present address: WuXi NextCODE, Cambridge, MA, USA.
‡ Present address: Illumina Inc., San Diego, CA, USA.
§Corresponding author. Peter J. Park, Christopher A. Walsh
* These authors contributed equally to this work.
Neurons live for decades in a postmitotic state, their genomes susceptible to DNA damage. Here we survey the landscape of somatic single-nucleotide variants (SNVs) in the human brain. We identified thousands of somatic SNVs by single-cell sequencing of 36 neurons from the cerebral cortex of three normal individuals. Unlike germline and cancer SNVs, which are often caused by errors in DNA replication, neuronal mutations appear to reflect damage during active transcription. Somatic mutations create nested lineage trees, allowing them to be dated relative to developmental landmarks and revealing a polyclonal architecture of the human cerebral cortex. Thus, somatic mutations in the brain represent a durable and ongoing record of neuronal life history, from development through postmitotic function.