More than 2 million years ago, a segment of DNA flipped its orientation in the genome of some of our ancestors. Scientists are now investigating whether that ancient genetic change could help explain why people have different risks of developing Alzheimer's disease and other neurodegenerative disorders.
The DNA change occurred in the MAPT locus, which contains the gene that encodes tau. Tau is a protein strongly associated with Alzheimer's disease and related conditions known as tauopathies.