Many Cases of Dementia May Arise From Non-Inherited DNA 'Spelling Mistakes'

A study published in Nature Communications suggests many dementia cases may not be the result of hereditary, but caused by spontaneous errors in DNA that occur as cells divide and reproduce, reports Medical Xpress . The investigators theorized that clusters of brain cells containing spontaneous genetic errors could trigger production of misfolded proteins with the potential to spread throughout the brain, eventually causing neurodegenerative disease. The team analyzed 173 tissue samples from the Newcastle Brain Tissue Resource in the U.K., derived from 54 individual brains. The brains were of 14 healthy individuals, 20 patients with Alzheimer's, and 20 persons with Lewy body dementia. The researchers sequenced 102 genes in the brain cells more than 5,000 times, and discovered spontaneous "somatic mutations" in 27 brains, including both healthy and diseased brains. The implication is that the mutations would have arisen during the developmental phase while the embryo is growing in the womb. The application of mathematical modeling to these results suggests that "islands" of brain cells containing these potentially important mutations are likely to be common in the general population. "These mutations likely form when our brain develops before birth — in other words, they sit there waiting to cause problems when we are older," says University of Cambridge Professor Patrick Chinnery.