Alzheimer’s Disease Is More Prevalent In People With Down Syndrome Due To Chromosome 21 Extra Genes

Alzheimer’s Disease Is More Prevalent In People With Down Syndrome Due To Chromosome 21 Extra Genes

Researchers are coming a little closer to grasping which genes are the culprit for the premature occurrence of Alzheimer’s disease in individuals with Down syndrome, according to new research conducted by Francis Crick Institute and UCL scientists in London, UK, in collaboration with an international team of researchers. They managed to discover the genes that link Alzheimer’s disease to the Down syndrome.

Approximately 1 in 800 children are born with Down syndrome, which arises in persons who have an extra set of chromosomes 21. By the age of 60, around 66% of people with Down syndrome develop Alzheimer’s disease, prematurely.

The high rates of Alzheimer’s in individuals with Down syndrome are currently suspected to be due to a unique gene on chromosome 21 known as APP. Chromosome 21 holds 231 genes, but APP has long been the primary suspect for producing amyloid precursor proteins, which are responsible for the development of beta-amyloid proteins that bind together in the brain and are thought to cause Alzheimer’s disease.

Scientists discovered the genes that link Alzheimer’s disease to Down syndrome

The research group conducted a comparison of lab mice that yield APP-produced amyloid proteins either in conjunction with the human chromosome 21 or not. The purpose was to examine the impact of the APP gene on Alzheimer’s disease.

This way, they discovered that the mice with an additional set of chromosome 21 genes showed higher risks of developing Alzheimer’s disease prematurely, in comparison to the mice without an extra copy of chromosome 21 genes.

At more detailed examination, the mice with extra genes presented more beta-amyloid plaques in the brain’s region associated with memory. As a result, the mice’s memory tests yielded poorer results than the tests carried out by healthy mice.

The scientists surveyed what triggered the greater buildup of beta-amyloid plaques in the mice with extra copies of human chromosome 21 genes, and observed the presence of more than one type of beta-amyloid protein, concluding that this newly found amyloid protein is the culprit for the “lumps” production in the brain.


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