Increased DNA Copy Number Variation Mosaicism in Elderly Human Brain
Darine Villela1, Claudia K Suemoto2,3, Renata Leite3
1Human Genome and Stem Cells Research Center, Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, Rua do Matão 277, 05508-090 São Paulo, SP, Brazil.
Neural Plasticity
|July 28, 2018
Summary
Aging brains show increased DNA copy number variations (CNVs) compared to blood. These genetic changes, particularly deletions, are more frequent and larger in brain tissues, indicating significant genomic mosaicism in elderly individuals.
Area of Science:
- Genetics
- Neuroscience
- Genomics
Background:
- Aging is influenced by genetics, with neuronal cells exhibiting somatic genomic mosaicism, including DNA copy number variations (CNVs).
- CNVs are a key source of genetic variation linked to disorders and complex traits, potentially contributing to neuronal diversity and neurological diseases.
- The characteristics of somatic CNV mosaicism in healthy elderly brains remain largely uninvestigated.
Purpose of the Study:
- To investigate the features of somatic CNV mosaicism in nondiseased elderly brains.
- To compare the frequency and characteristics of CNVs in brain tissue versus blood.
- To characterize the extent of clonal mosaicism of CNVs within and between different brain regions.
Main Methods:
- Array-comparative genomic hybridization (array-CGH) analysis was used.
- Postmortem brain tissue (frontal cortex and cerebellum) and blood samples from elderly individuals were analyzed.
- Somatic CNVs were identified and characterized in terms of frequency, size, and location.
Main Results:
- A highly significant increase in the number of CNVs was observed in elderly brains compared to blood.
- Deletions were significantly more frequent in both the frontal cortex and cerebellum.
- Deletions were significantly larger in the cerebellum, with sizes ranging from 150-760 kb; most were common variants.
Conclusions:
- Nondiseased elderly brains exhibit extensive somatic CNV mosaicism, with a notable increase in deletions compared to blood.
- This mosaicism, particularly clonal expansion of CNVs, represents a previously uncharacterized type of genomic variation in the human brain.
- These findings provide new insights into brain complexity, neuronal diversity, and the potential role of CNVs in neurological functions and diseases.
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