Almost half of world’s adults aged 85 and over have Alzheimer’s Disease.
The amyloid-B precursor protein (APP) plays a key role in the development of the amyloid plaques that are the hallmark of Alzheimer’s disease. Now, researchers claim to have identified thousands of genetic variants of the APP gene that codes for the protein in the brains of patients with the most common form of Alzheimer’s disease, known as late-onset or sporadic AD (SAD).
The study reveals for the first time how this genetic variation occurs – by a mechanism involving the enzyme reverse transcriptase, the same type of enzyme used by HIV to infect cells.
APP forms plaques in the brain, as shown above in a light micrograph.
Our findings provide a scientific rationale for immediate clinical evaluations of HIV antiretroviral therapies in people with AD,’ says Jerold Chun, senior VP of Neuroscience Drug Discovery at Sanford Burnham Prebys Medical Discovery Unit (SBP), an idea that the researchers say is supported by the relative absence of proven AD in ageing HIV patients on antiretroviral medication.
The APP gene variants were created by reverse transcription, the researchers note, when RNA acts as a template to form complementary DNA sequences that are then reinserted back into the original genome.
Discovery of possible Alzheimer’s treatment. Video: Sanford Burnham Prebys Medical Discovery Institute
This process of gene recombination – which occurs each time cells divide to make new ones – has not previously been reported in nerve cells (neurons) in the brain but could also help to explain the complexity and diverse functions of our brain cells.